# List of plant genera named for people (K–P)

Since the first printing of Carl Linnaeus's Species Plantarum in 1753, plants have been assigned one epithet or name for their species and one name for their genus, a grouping of related species. Thousands of plants have been named for people, including botanists and their colleagues, plant collectors, horticulturists, explorers, rulers, politicians, clerics, doctors, philosophers and scientists. Even before Linnaeus, botanists such as Joseph Pitton de Tournefort, Charles Plumier and Pier Antonio Micheli were naming plants for people, sometimes in gratitude for the financial support of their patrons.
Early works researching the naming of plant genera include an 1810 glossary by Alexandre de Théis [fr] and an etymological dictionary in two editions (1853 and 1856) by Georg Christian Wittstein. Modern works include The Gardener's Botanical by Ross Bayton, Index of Eponymic Plant Names and Encyclopedia of Eponymic Plant Names by Lotte Burkhardt, Plants of the World by Maarten J. M. Christenhusz (lead author), Michael F. Fay and Mark W. Chase, The A to Z of Plant Names by Allan J. Coombes, the four-volume CRC World Dictionary of Plant Names by Umberto Quattrocchi, and Stearn's Dictionary of Plant Names for Gardeners by William T. Stearn; these supply the seed-bearing genera listed in the first column below. Excluded from this list are genus names not accepted (as of January 2021) at Plants of the World Online, which includes updates to Plants of the World (2017).

## Key

    Ba = listed in Bayton's The Gardener's Botanical
    Bt = listed in Burkhardt's Encyclopedia of Eponymic Plant Names
    Bu = listed in Burkhardt's Index of Eponymic Plant Names
    Ch = listed in Christenhusz's Plants of the World
    Co = listed in Coombes's The A to Z of Plant Names
    Qu = listed in Quattrocchi's CRC World Dictionary of Plant Names
    St = listed in Stearn's Dictionary of Plant Names for Gardeners
In addition, Burkhardt's Index is used as a reference for every row in the table, except as noted.

## Genera

* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
* K
* L
* M
* N
* O
* P
* Q
* R
* S
* T
* U
* V
* W
* X
* Y
* Z
Genera :
| Genus | Person honored | Plant family | Ref |
| Kabuyea | Christine H. Sophie Kabuye (b. 1938), director of the East African Herbarium in Nairobi, Kenya | Tecophilaeaceae | Bu |
| Kadenicarpus | Nikolai Nikolayevich Kaden (1914–1976), Russian botanist | Cactaceae | Bu |
| Kadua | Kadu (19th century), an advisor to the king of Micronesia; joined one of Otto von Kotzebue's expeditions | Rubiaceae | Bu |
| Kaempferia | Engelbert Kaempfer (1651–1716) | Zingiberaceae | St |
| Kageneckia | Johann Friedrich von Kageneck (1741–1800), Austrian ambassador in Stockholm, Copenhagen, London and Madrid; a botanical patron | Rosaceae | Bu |
| Kailarsenia | Kai Larsen (1926–2012) | Rubiaceae | Qu |
| Kaisupeea | Supee Saksuwan Larsen (b. 1939) and her husband Kai Larsen (1926–2012) | Gesneriaceae | Bu |
| Kajewskiella | Sethrick Frank Kajewski (1904–1970), plant collector in Australia and the South Pacific | Rubiaceae | Bu |
| Kalbreyeriella | Guillermo Kalbreyer (1847–1912) | Acanthaceae | Bu |
| Kallstroemia | Anders Kallstroem (1733–1812), Scandinavian botanist | Zygophyllaceae | Bu |
| Kalmia | Pehr Kalm (1716–1779) | Ericaceae | Co |
| Kamelinia | Rudolf Vladimirovich Kamelin (1938–2016), Russian botanist at the university in Saint Petersburg; interested in plant systematics and distribution | Apiaceae | Bu |
| Kardomia | Karel Domin (1882–1953) | Myrtaceae | Bu |
| Karelinia | Grigory Karelin (1801–1872), Russian naturalist; studied botany under Eduard Friedrich Eversmann; explored Siberia, the Kyrgyz steppes and the Caspian shore | Asteraceae | Bu |
| Karina | Karin Tanguy, granddaughter of Raymond Boutique (1906–1985) | Gentianaceae | Bu |
| Karpatiosorbus | Zoltán Kárpáti (1909–1972), Hungarian (Geo-)Botanist, Taxonomist, Dendrologist and specialist in Sorbus | Rosaceae | Bt |
| Karwinskia | Wilhelm Friedrich Karwinsky von Karwin (1780–1855) | Rhamnaceae | Bu |
| Kaufmannia | Konstantin Petrovich von Kaufmann (1818–1882), colonial administrator | Primulaceae | Bu |
| Kaunia | Edward Gordon Kaun (1922–1992), American researcher from Baltimore, Maryland; assisted Robert Merrill King and others | Asteraceae | Bu |
| Kayea | Robert Kaye Greville (1794–1866) | Calophyllaceae | Bu |
| Kearnemalvastrum | Thomas Henry Kearney (1874–1956) | Malvaceae | Bu |
| Keayodendron | Ronald William John Keay (1920–1998) | Phyllanthaceae | Bu |
| Keckiella | David D. Keck (1903–1995) | Plantaginaceae | Ba |
| Keetia | Johan Diederik Möhr Keet (1882–1976), South African botanist and plant collector; forest director in the Transvaal | Rubiaceae | Bu |
| Kefersteinia | Christoph Ludwig Albrecht Keferstein (1792–1872), German entrepreneur; orchid enthusiast who maintained a botanical park | Orchidaceae | Bu |
| Kegeliella | Hermann Aribert Heinrich Kegel (1819–1856), German gardener at a botanical garden in Halle | Orchidaceae | Bu |
| Kelleria | possibly Johann Christoph Keller (1737–1795), German illustrator and engraver, or Johann Christoph Keller (fl. c. 1590), Austrian mathematician, or Engelhardt Keller, who wrote Über den Wein ("On Wine", 1838) | Thymelaeaceae | Bu |
| Kelleronia | Conrad Keller (1848–1930), Swiss zoologist and botanist, professor of zoology at ETH Zurich | Zygophyllaceae | Bu |
| Kellochloa | Elizabeth Anne Kellog (b.1951) an American botanist from Harvard University | Poaceae | Bt |
| Kelloggia | Albert Kellogg (1813–1887) | Rubiaceae | Qu |
| Kelseya | Francis Duncan Kelsey (1849–1905), reverend; authority on the plants of the US state of Montana | Rosaceae | Qu |
| Kemulariella | Liubov Kemularia-Nathadze (1891–1985) | Asteraceae | Bu |
| Kendrickia | George Henry Kendrick Thwaites (1811–1882) | Melastomataceae | Bu |
| Kengyilia | Yi Li Keng (1898–1975) | Poaceae | Bu |
| Kennedia | John Kennedy (1759–1842), original partner of Lee and Kennedy (nurseries) | Fabaceae | St |
| Kentiopsis | Willem Kent (1779–1827), Dutch head gardener of the botanical garden of the former university in Harderwijk and botanical garden curator in Bogor in present-day Indonesia | Arecaceae | Bu |
| Keraymonia | Monique Keraudren (1928–1981) | Apiaceae | Bu |
| Kerbera | Edmund Kerber (c. 1848 – c. 1887), plant collector in Mexico and China | Apocynaceae | Bu |
| Kermadecia | Jean-Michel Huon de Kermadec (1748–1793), naval officer | Proteaceae | Bu |
| Kernera | Johann Simon von Kerner (1755–1830) | Brassicaceae | St |
| Kerria | William Kerr (1799–1814) | Rosaceae | Co |
| Kerriochloa | Arthur Francis George Kerr (1877–1942) | Poaceae | Bu |
| Kerriodoxa | Arthur Francis George Kerr (1877–1942) | Arecaceae | Bu |
| Kerriothyrsus | Arthur Francis George Kerr (1877–1942) | Melastomataceae | Bu |
| Keteleeria | Jean Baptiste Keteleer (1813–1903), French horticulturalist | Pinaceae | St |
| Keysseria | Christian Keyser (1877–1961) | Asteraceae | Bu |
| Kickxia | Jean Kickx (1803–1864) | Plantaginaceae | St |
| Kielmeyera | Carl Friedrich Kielmeyer (1765–1844) | Calophyllaceae | Bu |
| Kiggelaria | Franz Kiggelaer (1648–1722) | Achariaceae | Bu |
| Killickia | Donald Joseph Boomer Killick (1926–2008), South African botanist at Kew Gardens and elsewhere | Lamiaceae | Bu |
| Killipia | Ellsworth Paine Killip (1890–1968) | Melastomataceae | Bu |
| Kingdonia | Selina Mary Ward (born Kingdon) (1854–1922), wife of Harry Marshall Ward | Circaeasteraceae | Bu |
| Kinghamia | Diana Louise Kingham (fl. 1976); wrote a study on African pollen at the University of Leeds in England | Asteraceae | Bu |
| Kingia | Phillip Parker King (1791–1856) and Philip Gidley King (1758–1808) | Dasypogonaceae | Bu |
| Kingianthus | Robert Merrill King (1930–2007), American botanist who worked at the National Museum of Natural History in Washington, D.C. | Asteraceae | Bu |
| Kippistia | Richard Kippist (1812–1882) | Asteraceae | Qu |
| Kirkbridea | Joseph Harold Kirkbride (b. 1943), American botanist who worked at the National Arboretum and as a curator at the Department of Agriculture herbarium | Melastomataceae | Bu |
| Kirkia | John Kirk (1832–1922) | Kirkiaceae | Bu |
| Kitagawia | Masao Kitagawa (1910–1995) | Apiaceae | Bu |
| Kitaibelia | Pál Kitaibel (1757–1817). Previously Kitaibela. | Malvaceae | Co |
| Kjellbergiodendron | Gunnar Konstantin Kjellberg (1885–1943), Swedish botanist who collected in Europe and around the Celebes Sea | Myrtaceae | Bu |
| Klackenbergia | Jens Klackenberg (b. 1951), Swedish professor of botany at Stockholm University | Gentianaceae | Bu |
| Klaineanthus | Théophile Klaine (1842–1911), French clergyman and plant collector | Euphorbiaceae | Bu |
| Klainedoxa | Théophile Klaine (1842–1911), French clergyman and plant collector | Irvingiaceae | Bu |
| Klaprothia | Martin Heinrich Klaproth (1743–1817) | Loasaceae | Bu |
| Klarobelia | Robert Elias Fries (1876–1966), Swedish botanist and mycologist, botanical garden director in Stockholm | Annonaceae | Bu |
| Klasea | Lars Magnus Klase (1722–1766), Swedish doctor in Jönköping, student of Carl Linnaeus | Asteraceae | Bu |
| Klattia | Friedrich Wilhelm Klatt (1825–1897) | Iridaceae | Bu |
| Kleinhovia | Christiaan Kleynhoff, later Lord van Enspijk (d. 1777), German-born Dutch doctor in the service of the Dutch West India Company; director of the medicinal garden of the Dutch East India Company in Jakarta | Malvaceae | Bu |
| Kleinia | Jacob Theodor Klein (1685–1759) | Asteraceae | St |
| Klossia | C. Boden Kloss (1877–1949) | Rubiaceae | Bu |
| Klotzschia | Johann Friedrich Klotzsch (1805–1860) | Apiaceae | Bu |
| Knautia | Christian Knaut (1656–1716) and his brother Christoph Knaut | Caprifoliaceae | Co |
| Knightia | Thomas Andrew Knight (1759–1838) | Proteaceae | St |
| Kniphofia | Johann Hieronymus Kniphof (1704–1763) | Asphodelaceae | Co |
| Knorringia | Olga Knorring (1887–1978) | Polygonaceae | Bu |
| Knowltonia | Thomas Knowlton (1692–1781) | Ranunculaceae | Bu |
| Knoxia | Robert Knox (1641–1720), sea captain | Rubiaceae | Bu |
| Kochummenia | Kizhakkedathu Mathai Kochummen (1931–1999), Indian-born Malaysian botanist at the Forest Research Institute Malaysia in Kepong; specialist in Malaysian trees | Rubiaceae | Bu |
| Koeberlinia | Christoph Ludwig Köberlin (1794–1862), German botanist and clergyman who researched plants near Memmingen and in the Alps | Koeberliniaceae | Bu |
| Koehneola | Bernhard Adalbert Emil Koehne (1848–1918) | Asteraceae | Qu |
| Koehneria | Bernhard Adalbert Emil Koehne (1848–1918) | Lythraceae | Qu |
| Koeleria | Georg Ludwig Koeler (1764–1807), German personal physician and professor of botany and medicine in Mainz; focused on grasses | Poaceae | Ba |
| Koellensteinia | Karl Kellner von Koellenstein (1807–1849), Austrian military officer who collected plants near Venice and Verona | Orchidaceae | Bu |
| Koelpinia | Alexander Bernhard Kölpin (1739–1801), German doctor and botanical garden director in Greifswald | Asteraceae | Bu |
| Koelreuteria | Joseph Gottlieb Kölreuter (1733–1806) | Sapindaceae | Co |
| Koenigia | Johann Gerhard König (1728–1785) | Polygonaceae | Bu |
| Koernickanthe | Friedrich August Körnicke (1828–1908) | Marantaceae | Bu |
| Kohautia | Franz Kohaut (d. 1822) | Rubiaceae | Bu |
| Kohleria | Johann Michael Kohler (1812–1884), Swiss teacher | Gesneriaceae | St |
| Komarovia | Vladimir Leontyevich Komarov (1869–1945) | Apiaceae | Bu |
| Koordersiochloa | Sijfert Hendrik Koorders (1863–1919), Dutch-Indonesian botanist and mycologist in Bogor, and herbarium director beginning in 1903 | Poaceae | Bu |
| Koordersiodendron | Sijfert Hendrik Koorders (1863–1919), Dutch-Indonesian botanist and mycologist in Bogor, and herbarium director beginning in 1903 | Anacardiaceae | Bu |
| Kopsia | Jan Kops (1765–1849) | Apocynaceae | Bu |
| Kopsiopsis | Jan Kops (1765–1849) | Orobanchaceae | Bu |
| Korshinskia | Sergéi Korzhinski (1861–1900), Russian botanist who studied plant distribution, professor at the university in Tomsk; later worked at a botanical garden and botanical museum in Saint Petersburg | Apiaceae | Bu |
| Korthalsella | Pieter Willem Korthals (1807–1892), Dutch botanist | Santalaceae | Bu |
| Korthalsia | Pieter Willem Korthals (1807–1892), Dutch botanist | Arecaceae | St |
| Kosteletzkya | Vincenz Kosteletzky (1801–1887), medical botanist in Prague (present-day Czech Republic) | Malvaceae | St |
| Kostermansia | André Joseph Guillaume Henri Kostermans (1906–1994) | Malvaceae | Bu |
| Kostermanthus | André Joseph Guillaume Henri Kostermans (1906–1994) | Chrysobalanaceae | Bu |
| Kotschya | Theodor Kotschy (1813–1866) | Fabaceae | Bu |
| Koyamaea | Tetsuo Michael Koyama (b. 1933), Japanese botanist at the New York Botanical Garden; specialist in Cyperaceae | Cyperaceae | Bu |
| Koyamasia | Hiroshige Koyama (b. 1937) | Asteraceae | Bu |
| Kozlovia | Pyotr Kozlov (1863–1935) | Apiaceae | Bu |
| Krameria | Wilhelm Heinrich Kramer (1724–1765) | Krameriaceae | Ch |
| Krapovickasia | Antonio Krapovickas (1921–2015) | Malvaceae | Qu |
| Krascheninnikovia | Stepan Krasheninnikov (1711–1755) | Amaranthaceae | Bu |
| Krasnovia | Andrey Krasnov (1862–1914), Russian naturalist; professor of geography and biology in Kharkiv, Ukraine; founded botanical gardens there and in Batumi in Georgia | Apiaceae | Bu |
| Krauseola | Johannes Krause (1900–1979), German botanist | Caryophyllaceae | Bu |
| Kraussia | Christian Ferdinand Friedrich Krauss (1812–1890) | Rubiaceae | Bu |
| Kremeriella | Jean Pierre Kremer (1812–1867), French doctor and botanist from Metz | Brassicaceae | Bu |
| Krigia | David Krieg (1667–1713), German physician and collector | Asteraceae | St |
| Krubera | Johann Julius Kruber (d. 1826), doctor and botanist in Moscow, Russia | Apiaceae | Bu |
| Krugiodendron | Karl Wilhelm Leopold Krug (1833–1898) | Rhamnaceae | Bu |
| Krukoviella | Boris Alexander Krukoff (1898–1983), Russian-born American botanist who collected in South America, West Africa and Sumatra; was later a curator at the herbarium of the New York Botanical Garden | Ochnaceae | Bu |
| Kubitzkia | Klaus Kubitzki (b. 1933) | Lauraceae | Bu |
| Kudoacanthus | Yūshun Kudō (1887–1932), Japanese professor of botany and botanical garden director in Taipei, Taiwan; founded a herbarium | Acanthaceae | Bu |
| Kudrjaschevia | Serafim Nikolaevich Kudrjaschev (1907–1943), botanical author | Lamiaceae | Bu |
| Kuepferia | Philippe Küpfer (b. 1942), Swiss professor of botany at the University of Neuchâtel; specialist in Gentianaceae and Ranunculaceae | Gentianaceae | Bu |
| Kuhlhasseltia | Heinrich Kuhl (1797–1821) and Johan Conrad van Hasselt (1797–1823) | Orchidaceae | Bu |
| Kuhlmanniodendron | João Geraldo Kuhlmann (1882–1958) | Achariaceae | Bu |
| Kummerowia | Heinrich Johannes Gotthilf Kummerow (1860–1929), Polish professor in Bromberg | Fabaceae | Bt |
| Kundmannia | Johann Christian Kundmann (1684–1751), German doctor in Wrocław with a large naturalist collection | Apiaceae | Bu |
| Kunhardtia | Henry Rudolf Kunhardt (1889–1963), president of a petroleum company in Venezuela; financed botanical expeditions for the New York Botanical Garden; also an orchid collector | Rapateaceae | Bu |
| Kunstleria | Jacob Heinrich Hermann Kunstler (1837–1887), German naturalist from Haldensleben; collected plants and insects in Australia, and plants in present-day Malaysia for a botanical garden in Kolkata | Fabaceae | Bu |
| Kuntheria | Carl Sigismund Kunth (1788–1850) | Colchicaceae | Qu |
| Kunzea | Gustav Kunze (1793–1851) | Myrtaceae | St |
| Kurzamra | Federico Kurtz (1854–1920) | Lamiaceae | Bu |
| Kutchubaea | Viktor Kochubey (1768–1834), statesman | Rubiaceae | Bu |
| Kydia | Robert Kyd (1746–1793) | Malvaceae | Bu |
| Kyhosia | Donald William Kyhos (1929–2022), American professor of botany at the University of California, Los Angeles; focused on the genetics of Asteraceae | Asteraceae | Bu |
| Kyrsteniopsis | Johann Jakob Kirsten (1710–1765), German doctor, botanist, chemist and theologian; professor and dean in Altdorf bei Nürnberg | Asteraceae | Bu |
| Labichea | Jean Jacques Labiche (1784–1819), French naval officer | Fabaceae | St |
| Labourdonnaisia | Bertrand-François Mahé de La Bourdonnais (1699–1753), colonial administrator | Sapotaceae | Bu |
| Labramia | Jonas David Labram (1785–1852), Swiss botanical artist and illustrator | Sapotaceae | Bu |
| Lachenalia | Werner de la Chenal (1736–1800), Swiss professor of botany | Asparagaceae | St |
| Lackeya | James A. Lackey (b. 1943), American botanist at Iowa State University and the Smithsonian Institution; specialist in Fabaceae and Phaseoleae | Fabaceae | Bu |
| Ladeania | LaDean H. Egan (b. 1949), mother of Ashley Noel Egan (b. 1977), the author of the genus | Fabaceae | Bu |
| Ladenbergia | Johann Philipp von Ladenberg (1769–1847), Prussian lawyer who founded an educational institute for the sons of underprivileged forest officials | Rubiaceae | Bu |
| Ladyginia | Veniamin Fedorovich Ladygin (1860–1932), Russian botanist who collected in East Asia | Apiaceae | Bu |
| Laelia | Laelia, one of the Vestal Virgins | Orchidaceae | St |
| Laennecia | René Laennec (1781–1826), doctor | Asteraceae | Bu |
| Laestadia | Carl Petter Laestadius (1835–1920), Swedish botanist and teacher in Umeå | Asteraceae | Bu |
| Lafoensia | João Carlos de Bragança e Ligne, 2nd Duke of Lafões (1719–1806) | Lythraceae | Bu |
| Lafuentea | Tadeo Lafuente (b. c. 1780), Spanish military doctor who wrote about yellow fever | Plantaginaceae | Bu |
| Lagascea | Mariano Lagasca (1776–1839) | Asteraceae | Bu |
| Lagerstroemia | Magnus von Lagerström (d. 1759), Swedish merchant and naturalist, and friend of Carl Linnaeus | Lythraceae | Co |
| Lagrezia | Adrien Rose Arnaud Lagrèze-Fossat (1814 or 1818 – 1874), French botanist and lawyer in Moissac | Amaranthaceae | Bu |
| Lagunaria | Andréa Laguna (d. 1560), Spanish botanist | Malvaceae | St |
| Lalldhwojia | Lall Dhwoj (fl. 1927–1930), plant collector | Apiaceae | Bu |
| Lallemantia | Julius Léopold Eduard Avé-Lallemant (1803–1867) | Lamiaceae | St |
| Lamanonia | Robert de Lamanon (1752–1787) | Cunoniaceae | Bu |
| Lamarckia | Jean-Baptiste Lamarck (1744–1829) | Poaceae | St |
| Lambertia | Aylmer Bourke Lambert (1761–1842) | Proteaceae | St |
| Lamiodendron | Herman Johannes Lam (1892–1977) | Bignoniaceae | Bu |
| Lamourouxia | Jean Vincent Félix Lamouroux (1779–1825) | Orobanchaceae | Bu |
| Lamyropappus | Claude Marie Louise de Lamyre-Moryy, Comtesse de Neuville (1754–1791), French wife of Dominique, comte de Cassini | Asteraceae | Bt |
| Lamyropsis | Claude Marie Louise de Lamyre-Moryy, Comtesse de Neuville (1754–1791), French wife of Dominique, comte de Cassini | Asteraceae | Bt |
| Lancea | John Henry Lance (1793–1878), English lawyer and botanist; a lawyer and judge in Suriname for six years; orchid enthusiast | Mazaceae | Bu |
| Landiopsis | Jérôme Lalande (1732–1807), astronomer | Rubiaceae | Bu |
| Landolphia | Jean-François Landolphe (1747–1825), naval officer | Apocynaceae | Bu |
| Langloisia | Auguste Berthélemy Langlois (1832–1900), French-born American clergyman and botanist | Polemoniaceae | Bu |
| Langsdorffia | Georg von Langsdorff (1774–1852) | Balanophoraceae | Qu |
| Lankesterella | Charles Herbert Lankester (1879–1969), English-born Costa Rican naturalist and botanist; coffee planter; specialist in orchids | Orchidaceae | Bu |
| Lankesteria | Edwin Lankester (1814–1874) | Acanthaceae | Bu |
| Lapageria | Empress Joséphine (Marie de La Pagerie) | Philesiaceae | Co |
| Lapeirousia | Philippe-Isidore Picot de Lapeyrouse (1744–1818) | Iridaceae | St |
| Lapiedra | Maria Josefa Martínez (1775–1858), Spanish botanist | Amaryllidaceae | Bu |
| Laportea | possibly named for M. Laporte, a companion of Charles Gaudichaud-Beaupré on his botanical voyage on the ship Uranie | Urticaceae | St |
| Lardizabala | Manuel de Lardizábal y Uribe (1744–1824), politician | Lardizabalaceae | Ch |
| Larrea | Juan Antonio Hernández Pérez de Larrea (1731–1803) | Zygophyllaceae | St |
| Larryleachia | Leslie Charles Leach (1909–1996) | Apocynaceae | Bu |
| Larsenaikia | Kai Larsen (1926–2012) | Rubiaceae | Bu |
| Larsenianthus | Kai Larsen (1926–2012) | Zingiberaceae | Bu |
| Lasjia | Lawrence Alexander Sidney Johnson (1925–1997) | Proteaceae | Bu |
| Lastarriaea | José Victorino Lastarria (1817–1888), politician | Polygonaceae | Bu |
| Lasthenia | Lastheneia of Mantinea (4th century BC), student of Plato | Asteraceae | St |
| Latouchea | John David Digues La Touche (1861–1935) and his wife, née Caroline Dawson Focken (c. 1871 – c. 1945) | Gentianaceae | Bu |
| Latrobea | Charles La Trobe (1801–1875), colonial administrator who established a botanical garden | Fabaceae | Bu |
| Laubertia | Carlo Lauberg (1762–1834), French military apothecary from Naples, Italy; senior health inspector in civil service (succeeding Antoine-Augustin Parmentier); wrote about Cinchona and quinine | Apocynaceae | Bu |
| Launaea | Jean Claude Mien Mordant de Launey (1750–1816), French lawyer and natural scientist; librarian at the National Museum of Natural History | Asteraceae | Bu |
| Laurembergia | Peter Lauremberg (1585–1639), polymath | Haloragaceae | Bu |
| Lauterbachia | Carl Adolf Georg Lauterbach (1864–1937) | Monimiaceae | Bu |
| Lavatera | Johann Lavater (1611–1691) | Malvaceae | St |
| Lavigeria | Charles Lavigerie (1825–1892), Roman Catholic cardinal | Icacinaceae | Bu |
| Lavoisiera | Antoine Lavoisier (1743–1794), chemist | Melastomataceae | Bu |
| Lavrania | John Jacob Lavranos (b. 1926) | Apocynaceae | Bu |
| Lawrencella | Robert William Lawrence (1807–1833) | Asteraceae | Bu |
| Lawrencia | Robert William Lawrence (1807–1833) | Malvaceae | Bu |
| Lawsonia | Isaac Lawson (1704–1747) | Lythraceae | St |
| Laxmannia | Erik Laxmann (1737–1796) | Asparagaceae | Bu |
| Layia | George Tradescant Lay (1799–1845) | Asteraceae | St |
| Leandra | Leandro do Santíssimo Sacramento (1778–1829), Brazilian clergyman and botanist; botanical garden director in Rio de Janeiro | Melastomataceae | Bu |
| Leandriella | Jacques Désiré Leandri (1903–1982) | Acanthaceae | Bu |
| Leavenworthia | Melines Conklin Leavenworth (1796–1862), American doctor; collected plants in southern states and in Mexico | Brassicaceae | Bu |
| Lebeckia | Hendrik Julius Lebeck (1772–1800), Dutch botanist and plant collector; merchant in the service of the Dutch East India Company | Fabaceae | Bu |
| Lebronnecia | Guillaume Le Bronnec (1884–1968), French naturalist in the Marquesas Islands | Malvaceae | Bu |
| Lebrunia | Jean Paul Antoine Lebrun (1906–1985), Belgian agricultural scientist and botanist at the university in Leuven | Clusiaceae | Bu |
| Lebruniodendron | Jean Paul Antoine Lebrun (1906–1985), Belgian agricultural scientist and botanist at the university in Leuven | Fabaceae | Bu |
| Lechea | Johan Leche (1704–1764), Swedish doctor and naturalist; professor of medicine in Turku | Cistaceae | Bu |
| Lecointea | Paul Georges Aimé Le Cointe (1870–1956), French botanist who worked in Brazil; director of a museum in Belém | Fabaceae | Qu |
| Lecokia | Henri Lecoq (1802–1871) | Apiaceae | Bu |
| Lecomtedoxa | Paul Henri Lecomte (1856–1934) | Sapotaceae | Bu |
| Lecomtella | Paul Henri Lecomte (1856–1934) | Poaceae | Bu |
| Ledebouria | Carl Friedrich von Ledebour (1785–1851) | Asparagaceae | Ba |
| Ledebouriella | Carl Friedrich von Ledebour (1785–1851) | Apiaceae | Bu |
| Ledenbergia | Johann Philipp von Ladenberg (1769–1847), Prussian lawyer who founded an educational institute for the sons of underprivileged forest officials | Petiveriaceae | Bu |
| Ledermanniella | Carl Ludwig Ledermann (1875–1958), Swiss botanist and garden designer; traveled in Kamerun (now Cameroon) and around the Pacific | Podostemaceae | Bu |
| Leea | James Lee (1715–1795) of Lee and Kennedy (nurseries) | Vitaceae | St |
| Leersia | Johann Georg Daniel Leers (1727 – c. 1774), German botanist and apothecary in Herborn, Hesse; taught pharmacology; collected plants in the area, especially grasses | Poaceae | Bu |
| Leeuwenbergia | Anthonius Josephus Maria Leeuwenberg (1930–2010) | Euphorbiaceae | Bu |
| Lefebvrea | Charlemagne Théophile Lefebvre (1811–1860), French naval officer and explorer; took part in a scientific expedition in Ethiopia | Apiaceae | Bu |
| Legenere | Edward Lee Greene (1843–1915) | Campanulaceae | Bu |
| Legousia | Bénigne Legouz de Gerland (1695–1774), French historian and botanist | Campanulaceae | Co |
| Legrandia | Carlos Maria Diego Enrique Legrand (1901–1986), Uruguayan naturalist and botanist; specialist in Portulacaceae and Myrtaceae; national museum director | Myrtaceae | Bu |
| Lehmanniella | Friedrich Carl Lehmann (1850–1903) | Gentianaceae | Bu |
| Leibnitzia | Gottfried Wilhelm Leibniz (1646–1716), philosopher and mathematician | Asteraceae | Bu |
| Leiboldia | Friedrich Ernst Leibold (1804–1864) | Asteraceae | Bu |
| Leidesia | Carl Friedrich Seidel (d. 1898), German painter and botanist, and/or Jacob Friedrich Seidel (1789–1860), German gardener, and/or Johann Heinrich Seidel (1744–1815), German court gardener | Euphorbiaceae | Bu |
| Leipoldtia | C. Louis Leipoldt (1880–1947), poet | Aizoaceae | Bu |
| Leitneria | Edward Frederick Leitner (1812–1838) | Simaroubaceae | St |
| Lelya | Hugh Vandervaes Lely (1891–1947), English botanist and forester in Nigeria | Rubiaceae | Bu |
| Lemaireocereus | Charles Antoine Lemaire (1800–1871) | Cactaceae | Bu |
| Lemeltonia | Elton Martinez Carvalho Leme (b. 1960), Brazilian botanist, specialist in Brazilian Bromeliaceae at a herbarium in Rio de Janeiro | Bromeliaceae | Bu |
| Lemooria | Spencer Le Marchant Moore (1850–1931) | Asteraceae | Bu |
| Lennea | Peter Joseph Lenné (1789–1866) | Fabaceae | Bu |
| Lennoa | Joaquín Leño, Mexican independence fighter | Boraginaceae | Bu |
| Lenwebbia | Leonard Webb (1920–2008) | Myrtaceae | Bu |
| Lenzia | Harald Othmar Lenz (1798–1870), German teacher and naturalist in Thuringia; historian of science; specialist in fungi and sponges | Montiaceae | Bu |
| Leobordea | Léon de Laborde (1807–1869) | Fabaceae | Bu |
| Leocereus | Antonio Pacheco Leão (1872–1931), Brazilian botanist, botanical garden director in Rio de Janeiro | Cactaceae | Bu |
| Leonardoxa | Jean Joseph Gustave Léonard (1920–2013), Belgian botanist at a botanical garden in Brussels | Fabaceae | Bu |
| Leonia | Francisco León, lawyer; patron of the botanists Hipólito Ruiz López and José Antonio Pavón Jiménez | Violaceae | Bu |
| Leonis | Frère León (1871–1955) | Asteraceae | Bu |
| Leopoldia | Leopold II, Holy Roman Emperor (1747–1792) | Asparagaceae | Bu |
| Leopoldinia | Maria Leopoldina of Austria (1797–1826) | Arecaceae | Qu |
| Lepechinia | Ivan Lepyokhin (1740–1802) | Lamiaceae | Bu |
| Lepechiniella | Ivan Lepyokhin (1740–1802) | Boraginaceae | Bu |
| Lepinia | Jules Joseph Lépine (1817–1884), French naval apothecary | Apocynaceae | Bu |
| Lepiniopsis | Jules Joseph Lépine (1817–1884), French naval apothecary | Apocynaceae | Bu |
| Leplaea | Edmond Leplae (1868–1941), Belgian agricultural engineer, professor of agriculture in Liège | Meliaceae | Bu |
| Lerchea | Johann Jakob Lerche (1703–1780), German-born Russian military doctor and botanist in Saint Petersburg | Rubiaceae | Bu |
| Lereschia | Louis François Jules Rodolphe Leresche (1808–1885), Swiss clergyman, botanist and plant collector in the Canton of Vaud | Apiaceae | Bu |
| Leretia | Jean de Léry (c. 1536 – c. 1613), clergyman | Icacinaceae | Bu |
| Lescaillea | Lescaille, coffee grower | Asteraceae | Bu |
| Leschenaultia | Jean-Baptiste Leschenault de La Tour (1773–1826) | Goodeniaceae | Bu |
| Lespedeza | Vicente Manuel de Céspedes (1721? – 1794), colonial administrator | Fabaceae | Co |
| Lessertia | Jules Paul Benjamin Delessert (1773–1847) | Fabaceae | Bu |
| Lessingia | Gotthold Ephraim Lessing (1729–1781), writer, and his grandnephews Karl Friedrich Lessing (1808–1880), painter, and Christian Friedrich Lessing (1809–1862) | Asteraceae | Bu |
| Lessingianthus | Christian Friedrich Lessing (1809–1862) | Asteraceae | Bu |
| Letestua | Georges Marie Patrice Charles Le Testu (1877–1967), French colonial administrator in tropical Africa; later at a botanical garden in Caen | Sapotaceae | Bu |
| Letestudoxa | Georges Marie Patrice Charles Le Testu (1877–1967), French colonial administrator in tropical Africa; later at a botanical garden in Caen | Annonaceae | Bu |
| Letestuella | Georges Marie Patrice Charles Le Testu (1877–1967), French colonial administrator in tropical Africa; later at a botanical garden in Caen | Podostemaceae | Bu |
| Lettowianthus | Paul von Lettow-Vorbeck (1870–1964), army officer | Annonaceae | Bu |
| Leuchtenbergia | Maximilian de Beauharnais, 3rd Duke of Leuchtenberg (1781–1824) | Cactaceae | St |
| Leuenbergeria | Beat Ernst Leuenberger (1946–2010), Swiss curator of tropical collections at a botanical garden in Berlin; specialist in Pereskioideae | Cactaceae | Bu |
| Leunisia | Johannes Leunis (1802–1873), German clergyman and botanist in Hildesheim; taught natural history and geography | Asteraceae | Bu |
| Leutea | Gerfried Horand Leute (b. 1941), Austrian botanist, botanical curator at the Natural History Museum, Vienna | Apiaceae | Bu |
| Leuzea | Joseph-Philippe-François Deleuze (1753–1835) | Asteraceae | Bu |
| Levenhookia | Antonie van Leeuwenhoek (1632–1723) | Stylidiaceae | Bu |
| Levieria | Emilio Levier (1839–1911), Swiss-born Italian botanist, mycologist and plant collector in Florence | Monimiaceae | Bu |
| Lewisia | Meriwether Lewis (1774–1809), explorer | Montiaceae | Co |
| Lewisiopsis | Meriwether Lewis (1774–1809), explorer | Montiaceae | Bu |
| Leycesteria | William Leycester (1775–1831), judge and horticulturist in Bengal | Caprifoliaceae | Co |
| Leysera | Friedrich Wilhelm von Leysser (1731–1815) | Asteraceae | Bu |
| Liberatia | Liberato Joaquim Barroso (1900–1949), Brazilian botanist and agronomist | Acanthaceae | Bu |
| Libertia | Marie-Anne Libert (1782–1865) | Iridaceae | Co |
| Lichtensteinia | Hinrich Lichtenstein (1780–1857) | Apiaceae | Bu |
| Lidbeckia | Eric Gustav Lidbeck (1724–1803), Swedish botanist, student of Carl Linnaeus, curator of a botanical garden and professor of natural history at Lund University | Asteraceae | Bu |
| Liebigia | Justus von Liebig (1803–1873) | Gesneriaceae | Bu |
| Lijndenia | D. W. J. C. Baron Van Lijnden (1813–1852), administrator in Bogor in the former Dutch East Indies (present-day Indonesia); supported botanical research | Melastomataceae | Bu |
| Lilaeopsis | Alire Raffeneau Delile (1778–1850) | Apiaceae | Qu |
| Limahlania | Ah-Lan Lim, Malaysian Botanist and Professor at the University of Malaysia in Kuala Lumpur | Gentianaceae | Bt |
| Lindackeria | Johann Thaddaeus Lindacker (1768–1816), Bohemian mineralogist from Banská Štiavnica; collected plants for his herbarium | Achariaceae | Bu |
| Lindelofia | Friedrich von Lindelof (1794–1882), German botanical patron (c. 1850). | Boraginaceae | St |
| Lindenbergia | Johann Bernhard Wilhelm Lindenberg (1781–1851) | Orobanchaceae | Bu |
| Lindera | Johan Linder (1678–1724), Swedish botanist | Lauraceae | Co |
| Lindernia | Franz Balthasar von Lindern (1682–1755), French doctor and botanist in Strasbourg; university botanical garden director | Linderniaceae | Bu |
| Linderniella | Franz Balthasar von Lindern (1682–1755), French doctor and botanist in Strasbourg; university botanical garden director | Linderniaceae | Bu |
| Lindheimera | Ferdinand Lindheimer (1801–1879) | Asteraceae | St |
| Lindleya | John Lindley (1799–1865) | Rosaceae | Bu |
| Lindmania | Carl Axel Magnus Lindman (1856–1928) | Bromeliaceae | Bu |
| Lindsayomyrtus | Lindsay Stuart Smith (1917–1970) | Myrtaceae | Bu |
| Lingelsheimia | Alexander von Lingelsheim (1874–1937) | Phyllanthaceae | Bu |
| Linnaea | Carl Linnaeus (1707–1778) | Caprifoliaceae | Co |
| Linnaeosicyos | Carl Linnaeus (1707–1778) | Cucurbitaceae | Bu |
| Linzia | Johann Michael Linz (c. 1770 – 1855), German botanist, entomologist, royal secretary and tax supervisor in Speyer | Asteraceae | Bu |
| Lippia | Augustin Lippi (1678–1705) | Verbenaceae | St |
| Lipschitziella | Sergej Julievitsch Lipschitz (1905–1983), Russian botanist, bibliographer and historian in present-day Saint Petersburg | Asteraceae | Bu |
| Lipskya | Vladimir Lipsky (1863–1937) | Apiaceae | Bu |
| Lisaea | Domenico Lisa (1801–1867), Italian botanist, head gardener at a botanical garden in Turin | Apiaceae | Bu |
| Listia | Friedrich Ludwig List (b. 1799), Prussian botanist and teacher | Fabaceae | Bu |
| Littledalea | St. George Littledale (1851–1931) | Poaceae | Bu |
| Litwinowia | Dmitry Litvinov (1854–1929) | Brassicaceae | Bu |
| Livistona | Patrick Murray, Baron of Livingston, whose 17th-century garden stocked the Edinburgh Botanic Garden | Arecaceae | St |
| Llagunoa | Eugenio de Llaguno y Amírola (1724–1799), Spanish politician | Sapindaceae | Bu |
| Llerasia | Lleras, a supporter of natural science in New Granada (present-day Colombia) | Asteraceae | Bu |
| Lobelia | Matthias de l'Obel (1538–1616) | Campanulaceae | Co |
| Lockhartia | David Lockhart (1786–1846) | Orchidaceae | St |
| Lodoicea | Louis XV (1710–1774) | Arecaceae | St |
| Loefgrenianthus | Johan Albert Constantin Löfgren (1854–1918) | Orchidaceae | Bu |
| Loeflingia | Pehr Löfling (1729–1756) | Caryophyllaceae | Bu |
| Loeselia | Johannes Loesel (1607–1655), German doctor and botanist, professor of medicine in Königsberg (present-day Kaliningrad) | Polemoniaceae | St |
| Loeseliastrum | Johannes Loesel (1607–1655), German doctor and botanist, professor of medicine in Königsberg (present-day Kaliningrad) | Polemoniaceae | Bu |
| Loesenera | Ludwig Eduard Theodor Loesener (1865–1941) | Fabaceae | Bu |
| Loeseneriella | Ludwig Eduard Theodor Loesener (1865–1941) | Celastraceae | Bu |
| Loewia | Ernst Loew (1843–1908), German botanist and teacher | Passifloraceae | Bu |
| Logania | James Logan (1674–1751) | Loganiaceae | Ch |
| Loheria | August Loher (1874–1930), German pharmacist and botanist | Primulaceae | Bu |
| Longetia | François Achille Longet (1811–1871), anatomist | Picrodendraceae | Bu |
| Lonicera | Adam Lonicer (1528–1586) | Caprifoliaceae | Co |
| Lopezia | Tomás Lopez, Spanish botanist and writer c. 1540 | Onagraceae | St |
| Lopriorea | Giuseppe Lopriore (1865–1928), Italian professor of botany at the institute of oenology in Catania and botanical garden director there; director of the agricultural research station in Modena | Amaranthaceae | Bu |
| Lorandersonia | Loran Crittenden Anderson (b. 1936), American botanist and plant taxonomist; professor at Florida State University; worked on Asteraceae and Cannabis | Asteraceae | Bu |
| Lordhowea | Ontong Java Atoll, formerly the Lord Howe Atoll in the Solomon Islands, named for Richard Howe, 1st Earl Howe (1726–1799) | Asteraceae | Bt |
| Lorentzianthus | Paul Günther Lorentz (1835–1881) | Eupatorieae | Bt |
| Lorenzia | Harri Lorenzi (b. 1949) | Araceae | Bt |
| Lorenzochloa | Lorenzo Raimundo Parodi (1895–1966) | Poaceae | Bt |
| Loudetia | Edward Loudet (1811–1867), German dentist and surgeon in Karlsruhe | Poaceae | Qu |
| Loudetiopsis | Edward Loudet (1811–1867), German dentist and surgeon in Karlsruhe | Poaceae | Qu |
| Louisiella | Jean Laurent Prosper Louis (1903–1947), Belgian botanist and professor of agronomy in Gembloux | Poaceae | Bu |
| Lourteigia | Alicia Lourteig (1913–2003) | Asteraceae | Bu |
| Lourtella | Alicia Lourteig (1913–2003) | Lythraceae | Bu |
| Lowia | Hugh Lowe (1824–1905), English colonial administrator and naturalist | Lowiaceae | Bu |
| Lozanella | José Filemón Guadalupe Lozano y Lozano (1877 – after 1940), Mexican traveling companion of Cyrus Pringle during his Mexican expedition | Cannabaceae | Bu |
| Lozania | Jorge Tadeo Lozano (1771–1816), politician | Lacistemataceae | Bu |
| Lucya | Rose Lucie (or Lucy) Dunal (1798–1827), sister of Michel Félix Dunal (1789–1856); investigated Rubiaceae in Montpellier | Rubiaceae | Bu |
| Ludovia | Maria Luisa of Parma (1751–1819) and her husband Charles IV of Spain (1748–1819) | Cyclanthaceae | Bu |
| Ludwigia | Christian Gottlieb Ludwig (1709–1773) | Onagraceae | Co |
| Lueckelia | Emil Lückel (b. 1927), German botanist and taxonomist from Frankfurt; specialist in orchids and president of the German Orchid Society | Orchidaceae | Bu |
| Lueddemannia | Gustav Adolf Lueddemann (1821–1884), German gardener in Paris, France; later had his own orchid nursery | Orchidaceae | Bu |
| Luehea | Carl Emil von der Luehe or Lühe (1751–1801), German botanist and chamberlain of Princess Caroline-Mathilde of Denmark; later a chamberlain in Vienna, Austria | Malvaceae | Bu |
| Lueheopsis | Carl Emil von der Luehe or Lühe (1751–1801), German botanist and chamberlain of Princess Caroline-Mathilde of Denmark; later a chamberlain in Vienna, Austria | Malvaceae | Bu |
| Luetkea | Friedrich Benjamin von Lütke (1797–1882) | Rosaceae | Bu |
| Luetzelburgia | Philipp von Luetzelburg (1880–1948), German pharmacist and botanist who traveled and collected in northeast Brazil | Fabaceae | Bu |
| Luisia | Luis de Torres (19th century), Spanish botanist | Orchidaceae | St |
| Lulia | Ángel Lulio Cabrera (1908–1999) | Asteraceae | Bu |
| Lumnitzera | István Lumnitzer (1750–1806), Hungarian doctor and botanist in present-day Bratislava, Slovakia | Combretaceae | Bu |
| Lunania | John Lunan (1771–1839) | Salicaceae | Bu |
| Lundellianthus | Cyrus Longworth Lundell (1907–1994) | Asteraceae | Bu |
| Lundia | Peter Wilhelm Lund (1801–1880) | Bignoniaceae | Bu |
| Lundinia | Roger Lundin (1955–2005), Swedish botanist at the natural history museum in Stockholm | Asteraceae | Bu |
| Lutheria | Harry Edward Luther (1952–2012), American botanist at the Marie Selby Botanical Gardens; specialist in Bromeliaceae | Bromeliaceae | Bu |
| Lutzia | Louis Charles Lutz (1871–1952), French pharmacist and botanist; professor with a focus on spore-bearing plants and microbiology in Paris | Brassicaceae | Bu |
| Luxemburgia | Charles Emmanuel Sigismond de Montmorency-Luxembourg (1774–1861), French duke of Piney-Luxembourg; botanical patron | Ochnaceae | Bu |
| Luzuriaga | Ignacio Maria Ruiz de Luzuriaga (1763–1822), Spanish doctor and botanist | Alstroemeriaceae | Bu |
| Lyallia | David Lyall (1817–1895) | Montiaceae | Bu |
| Lycoris | Volumnia Cytheris (fl. 1st century BC), Roman actress | Amaryllidaceae | St |
| Lymanbensonia | Lyman David Benson (1909–1993), American botanist, specialist in cactus | Cactaceae | Bu |
| Lymania | Lyman Bradford Smith (1904–1997) | Bromeliaceae | Bu |
| Lyonia | John Lyon (c. 1765 – c. 1816) | Ericaceae | St |
| Lyonothamnus | William Scrugham Lyon (1851–1916), American collector who sent specimens to Asa Gray | Rosaceae | Co |
| Lysakia | Martin A. Lysák (b.1973), Czech scientist and botanist | Brassicaceae | Bt |
| Lysimachia | probably Lysimachus (c. 360 BC – 281 BC), king | Primulaceae | Co |
| Maackia | Richard Maack (1825–1886) | Fabaceae | Co |
| Maasia | Paul Maas (b. 1939) | Annonaceae | Bu |
| Mabrya | Tom J. Mabry (1932–2015), American botanist and plant chemist and Professor at University of Texas at Austin | Plantaginaceae | Bt |
| Macadamia | John Macadam (1827–1865) | Proteaceae | St |
| Macairea | Isaac François Macaire, Swiss plant physiologist and chemist from Geneva | Melastomataceae | Bu |
| Macarthuria | William Macarthur (1800–1882) | Macarthuriaceae | Qu |
| Macbridea | James Macbride (1784–1817), American botanist and doctor in Charleston, South Carolina | Lamiaceae | Bu |
| Macbrideina | James Francis Macbride (1892–1976) | Rubiaceae | Bu |
| Macgregoria | John MacGregor (1828–1884), politician | Celastraceae | Bu |
| Mackaya | James Townsend Mackay (1775–1862) | Acanthaceae | St |
| Mackinlaya | John McKinlay (1819–1872) | Apiaceae | Bu |
| Maclaudia | Charles Maclaud (1866–1933), French doctor and zoologist; plant and animal collector | Apocynaceae | Bu |
| Macleania | John Maclean (1786–1857), Scottish merchant in Peru | Ericaceae | Ba |
| Macleaya | Alexander Macleay (1767–1848) | Papaveraceae | Co |
| Maclura | William Maclure (1763–1840) | Moraceae | Co |
| Maclurochloa | Floyd Alonzo McClure (1897–1970) | Poaceae | Bu |
| Maclurodendron | Floyd Alonzo McClure (1897–1970) | Rutaceae | Bu |
| Maclurolyra | Floyd Alonzo McClure (1897–1970) | Poaceae | Bu |
| Macphersonia | Pieter Daniël Eugenius MacPherson (1792–1846), politician, and Rose Marie Jeanne MacPherson, née van Meeuwen (1801–1889), noblewoman | Sapindaceae | Bu |
| Macrohasseltia | Johan Conrad van Hasselt (1797–1823) | Salicaceae | Bt |
| Macvaughiella | Rogers McVaugh (1909–2009) | Asteraceae | Bu |
| Magnolia | Pierre Magnol (1638–1715) | Magnoliaceae | Ch |
| Magonia | Mago Barca (243 BC – 203 BC), military officer | Sapindaceae | Bu |
| Maguireanthus | Bassett Maguire (1904–1991) | Melastomataceae | Qu |
| Maguireocharis | Bassett Maguire (1904–1991) | Rubiaceae | Qu |
| Maguireothamnus | Bassett Maguire (1904–1991) | Rubiaceae | Qu |
| Mahonia | Bernard McMahon (c. 1775 – 1816) | Berberidaceae | Co |
| Maillardia | Louis Gaspard Dominique Maillard (1780–1867), French engineer | Moraceae | Bu |
| Maingaya | Alexander Carroll Maingay (1836–1869) | Hamamelidaceae | Bu |
| Maireana | Joseph François Maire (1780–1867), Parisian plant collector who eventually gave his herbarium to Ernest Cosson | Amaranthaceae | Bu |
| Mairetis | René Maire (1878–1949) | Boraginaceae | Bu |
| Mairia | Louis Maire (d. 1885), German doctor and botanist who collected under the name of Mund and Maire | Asteraceae | Bu |
| Majidea | Majid bin Said of Zanzibar (c. 1834 – 1870) | Sapindaceae | Bu |
| Majovskya | Jozef Májovský, (1920–2012), Slovakian botanist and Professor of Botany in Bratislava | Rosaceae | Bt |
| Malcolmia | William Malcolm (d. 1798), London nurseryman who published a plant catalogue in 1771. Previously Malcomia. | Brassicaceae | St |
| Malesherbia | Guillaume-Chrétien de Lamoignon de Malesherbes (1721–1794), government minister | Passifloraceae | Bu |
| Malmea | Gustaf Oskar Andersson Malme (1864–1937) | Annonaceae | Bu |
| Malmeanthus | Gustaf Oskar Andersson Malme (1864–1937) | Asteraceae | Bu |
| Malouetia | Pierre Victor, baron Malouet (1740–1814) | Apocynaceae | Bu |
| Malperia | Edward Palmer (1829–1911) | Asteraceae | Bu |
| Malpighia | Marcello Malpighi (1628–1694) | Malpighiaceae | Ch |
| Malpighiodes | Marcello Malpighi (1628–1694) | Malpighiaceae | Bu |
| Maltebrunia | Conrad Malte-Brun (1775–1826) | Poaceae | Bu |
| Mammilloydia, synonym of Mammillaria | Francis Ernest Lloyd (1868–1947) | Cactaceae | Bu |
| Mandevilla | Henry John Mandeville (1773–1861), British minister in Buenos Aires | Apocynaceae | Co |
| Mandirola | Agostino Mandirola (d. 1661), Italian clergyman, naturalist and botanist with a focus on medicinal plants and citrus | Gesneriaceae | Bu |
| Manekia | Erik Leonard Ekman (1883–1931) | Piperaceae | Bu |
| Manettia | Saverio Manetti (1723–1785) | Rubiaceae | St |
| Mangenotiella | Georges Marie Mangenot (1899–1985), French botanist and Professor of Botany | Primulaceae | Bt |
| Mankyua | Man Kyu Pak (1906–1988), South Korean researcher and botanist (Pteridology) | Ophioglossaceae | Bt |
| Mannagettaea | Günther Beck von Mannagetta und Lerchenau (1856–1931) | Orobanchaceae | Bu |
| Manniella | Gustav Mann (1836–1916) | Orchidaceae | Bu |
| Manniophyton | Gustav Mann (1836–1916) | Euphorbiaceae | Bu |
| Mansoa | Antônio Luiz Patrício da Silva Manso (1788–1848) | Bignoniaceae | Bu |
| Mansonia | Francis Bruce Manson (c. 1850 – 1908), plant collector in Burma (present-day Myanmar) with the Indian Forest Service | Malvaceae | Bu |
| Maoutia | Emmanuel Le Maout (1799–1877) | Urticaceae | Bu |
| Mappia | Marcus Mappus (1666–1736), French doctor and botanist from Alsace; son of Marc or Marcus Mappus (1632–1701) | Icacinaceae | Bu |
| Mappianthus | Marcus Mappus (1666–1736), French doctor and botanist from Alsace; son of Marc or Marcus Mappus (1632–1701) | Icacinaceae | Bu |
| Maranta | Bartolomeo Maranta (1500–1571) | Marantaceae | Ch |
| Marantochloa | Bartolomeo Maranta (1500–1571) | Marantaceae | Bu |
| Marcania | Alexander Marcan (1883–1953), English collector of plants in Southeast Asia and Thailand | Acanthaceae | Bu |
| Marcelliopsis | Claudia Marcella Major (fl. 1st century BC), Roman noblewoman | Amaranthaceae | Bu |
| Marcetella | Adeodato Francisco Marcet (1875–1964), Spanish clergyman, botanist and agronomist; worked in a botanical garden in Blanes | Rosaceae | Bu |
| Marcetia | François Marcet (1803–1883), Swiss doctor, physiologist, inventor, and professor of physics | Melastomataceae | Bu |
| Marcgravia | Georg Marcgrave (1610–1644) | Marcgraviaceae | Qu |
| Marcgraviastrum | Georg Marcgrave (1610–1644) | Marcgraviaceae | Bu |
| Maresia | Paul Marès (1826–1900), French botanist who explored in Algeria and the Balearic Islands | Brassicaceae | Bu |
| Mareya | Étienne-Jules Marey (1830–1904), scientist | Euphorbiaceae | Bu |
| Mareyopsis | Étienne-Jules Marey (1830–1904), scientist | Euphorbiaceae | Bu |
| Margaretta | Margaret Laurie Grant (1834–1918), wrote about plants collected by her husband James Augustus Grant (1827–1892) on an expedition to find the source of the Nile | Apocynaceae | Bu |
| Marianthus | Princess Marie von Metternich, Austrian botanical patron | Pittosporaceae | Bu |
| Marina | La Malinche (1505–1530), interpreter for the conquistador Hernán Cortés | Fabaceae | Bu |
| Mariosousa | Mario Sousa Sánchez (1940–2017), Mexican botanist and plant collector, director of the university herbarium in Mexico City | Fabaceae | Bu |
| Markea | Jean-Baptiste Lamarck (1744–1829) | Solanaceae | Bu |
| Markhamia | Clements Markham (1830–1916) | Bignoniaceae | Bu |
| Marlothiella | Rudolf Marloth (1855–1931) | Apiaceae | Bu |
| Marlothistella | Rudolf Marloth (1855–1931) | Aizoaceae | Bu |
| Marquesia | Agostinho Sessinando Marques (1847–1925), plant collector in Angola | Dipterocarpaceae | Bu |
| Marsdenia | William Marsden (1754–1836), orientalist | Apocynaceae | St |
| Marshallia | Humphry Marshall (1722–1803) | Asteraceae | St |
| Marshalljohnstonia | Marshall Conring Johnston (b. 1930) | Asteraceae | Bu |
| Marshallocereus | William Taylor Marshall (1886–1957), American botanist, botanical garden director in Phoenix, Arizona; specialist in cactus | Cactaceae | Bu |
| Martellidendron | Ugolino Martelli (1860–1934) | Pandanaceae | Bu |
| Martensianthus | Martin Martens (1797–1863) | Rubiaceae | Bu |
| Marthella | Martha Urban, née Kurtz (1854–1920), wife of Ignatz Urban (1848–1931) | Burmanniaceae | Bu |
| Martianthus | Carl Friedrich Philipp von Martius (1794–1868) | Lamiaceae | Bu |
| Marticorenia | Clodomiro Fidel Segundo Marticorena (1929–2013), Chilean botanist and pharmacist, professor in Concepción and elsewhere | Asteraceae | Bu |
| Martinella | Joseph Martin (d. 1826) | Bignoniaceae | Bu |
| Martiodendron | Carl Friedrich Philipp von Martius (1794–1868) | Fabaceae | Bu |
| Martretia | Vincent Martret (1875–1904), French botanist who was responsible for a botanical research garden in the Central African Republic | Phyllanthaceae | Bu |
| Martynia | John Martyn (1699–1768) | Martyniaceae | Ch |
| Mascagnia | Paolo Mascagni (1755–1815), anatomist | Malpighiaceae | Bu |
| Masdevallia | José Masdevall (d. 1801), Spanish physician and botanist | Orchidaceae | St |
| Massonia | Francis Masson (1741–1805) | Asparagaceae | Bu |
| Mastersia | Maxwell T. Masters (1833–1907) | Fabaceae | Bu |
| Mastersiella | Maxwell T. Masters (1833–1907) | Restionaceae | Bu |
| Mathewsia | Andrew Mathews (1801–1841), English gardener, plant collector in Chile and Peru | Brassicaceae | Bu |
| Mathiasella | Mildred Esther Mathias (1906–1995) | Apiaceae | Ba |
| Mathieua | Louis Mathieu (1793–1867), German gardener; a director of an institute of gardening in Berlin | Amaryllidaceae | Bu |
| Matisia | Francisco Javier Matís (1763–1851) | Malvaceae | Bu |
| Matsumurella | Jinzō Matsumura (1856–1928) | Lamiaceae | Bu |
| Mattfeldanthus | Johannes Mattfeld (1895–1951), German botanist at the botanical museum in Dahlem, Berlin | Asteraceae | Bu |
| Mattfeldia | Johannes Mattfeld (1895–1951), German botanist at the botanical museum in Dahlem, Berlin | Asteraceae | Bu |
| Matthaea | Matteo di San Giuseppe (1612–1691), Italian doctor, botanist, linguist, and missionary in Palestine, Mesopotamia, the Malabar region and Persia (present-day Iran) | Monimiaceae | Bu |
| Matthiola | Pietro Andrea Mattioli (c. 1500 – 1577) | Brassicaceae | Co |
| Mattiastrum | Elisabeth von Matt (1762–1814), astronomer | Boraginaceae | Bu |
| Matudaea | Eizi Matuda (1894–1978) | Hamamelidaceae | Qu |
| Matudanthus | Eizi Matuda (1894–1978) | Commelinaceae | Qu |
| Maundia | John Maund (1823–1858), English-born Australian doctor and analytical chemist; worked in water analysis; was a doctor in Melbourne | Maundiaceae | Bu |
| Maurandella | Catalina Pancratia Maurandy, wife and colleague of Agostin Juan y Poveda (1770–1854), professor of botany and botanical garden director in Cartagena, Colombia | Plantaginaceae | Bu |
| Maurandya | Catalina Pancratia Maurandy, wife and colleague of Agostin Juan y Poveda (1770–1854), professor of botany and botanical garden director in Cartagena, Colombia | Plantaginaceae | Co |
| Mauria | Ernesto Mauri (1791–1836), Italian botanist and mycologist; professor of botany and botanical garden director in Rome | Anacardiaceae | Bu |
| Mauritiella | John Maurice, Prince of Nassau-Siegen (1604–1679) | Arecaceae | Bu |
| Maurocenia | Giovanni Francesco Morosini or Maurocenius (1658–1739), Venetian senator, botanical patron; had a large garden built up in Padua | Celastraceae | Bu |
| Maxburretia | Max Burret (1883–1964) | Arecaceae | Bu |
| Maxwellia | Maxwell T. Masters (1833–1907) | Malvaceae | Bu |
| Mayodendron | Richard Bourke, 6th Earl of Mayo (1822–1872) | Bignoniaceae | Bu |
| Mazaea | Manuel Gómez de la Maza y Jiménez (1867–1916), Cuban doctor; professor and director of the university botanical garden in Havana | Rubiaceae | Bu |
| Mcvaughia | Rogers McVaugh (1909–2009) | Malpighiaceae | Bu |
| Mecardonia | Antoni de Meca-Caçador-Cardona (1726–1788), 4th Marquess of Ciutadilla, Spanish botanist or enthusiast; donated lands to the city of Barcelona for a botanical garden | Plantaginaceae | Bu |
| Mechowia | Friedrich Wilhelm Alexander von Mechow (1831–1890) | Amaranthaceae | Bu |
| Medinilla | José de Medinilla, governor of Mauritius (c. 1820) | Melastomataceae | St |
| Medranoa | Francisco González Medrano (1939–2017), Mexican botanist | Asteraceae | Bt |
| Meeboldia | Alfred Meebold (1863–1952) | Apiaceae | Bu |
| Meehania | Thomas Meehan (1826–1901) | Lamiaceae | Bu |
| Megacorax | Peter H. Raven (b. 1936) | Onagraceae | Bu |
| Meineckia | Johann Ludwig Georg Meinecke (1721–1823), German physicist, biologist and teacher; professor of technology in Halle | Phyllanthaceae | Bu |
| Meistera | George Meister (1653–1713), German botanist and court gardener in Dresden for the Electorate of Saxony; also worked as a gardener in Japan | Zingiberaceae | Bu |
| Mellera | Charles James Meller (c. 1835 – 1869), English doctor, botanist and naturalist; joined one of David Livingstone's African expeditions | Acanthaceae | Bu |
| Melliniella | Adolf Mellin (c. 1873 – c. 1910), German botanist; collected plants in present-day Togo | Fabaceae | Bu |
| Mendoncia | José Francisco Miguel António de Mendonça (1725–1818), Roman Catholic cardinal | Acanthaceae | Bu |
| Menkea | Karl Theodor Menke (1791–1861) | Brassicaceae | Bu |
| Menonvillea | Nicolas-Joseph Thiéry de Menonville (1739–1780) | Brassicaceae | Bu |
| Mentzelia | Christian Mentzel (1622–1701), German doctor, botanist and sinologist | Loasaceae | Co |
| Merciera | Marie Philippe Mercier (1781–1831), French botanist; plant collector in Geneva | Campanulaceae | Bu |
| Meriania | Maria Sibylla Merian (1647–1717) | Melastomataceae | Bu |
| Merremia | Blasius Merrem (1761–1824) | Convolvulaceae | St |
| Merrilliodendron | Elmer Drew Merrill (1876–1956) | Icacinaceae | Bu |
| Merrilliopanax | Elmer Drew Merrill (1876–1956) | Araliaceae | Bu |
| Merrittia | Melvin Leroy Merritt (1879–1961), American forester for the Philippine Bureau of Forestry and the US Forest Service | Asteraceae | Bu |
| Mertensia | Franz Carl Mertens (1764–1831) | Boraginaceae | Co |
| Merwilla | Frederick Ziervogel Van der Merwe (1894–1968), South African doctor, botanist, and school inspector | Asparagaceae | Bu |
| Merxmuellera | Hermann Merxmüller (1920–1988) | Poaceae | Qu |
| Mesua | Masawaiyh (c. 777 – c. 857) | Calophyllaceae | Bu |
| Metasequoia | Sequoyah (c. 1770 – 1843), Cherokee linguist | Cupressaceae | Co |
| Metcalfia | Charles Russell Metcalfe (1904–1991), British researcher, botanist and plant anatomist; director of the Jodrell Laboratory at Kew Gardens | Poaceae | Bu |
| Metrodorea | Metrodorus (c. 1st century BC), student of a healer named Sabinus | Rutaceae | Bu |
| Metteniusa | Georg Heinrich Mettenius (1823–1866) | Metteniusaceae | Bu |
| Metternichia | Klemens von Metternich (1773–1859), diplomat | Solanaceae | Bu |
| Mexianthus | Ynes Mexia (1870–1938) | Asteraceae | Bu |
| Meyerophytum | Louis Gottlieb Meyer (1867–1958), German clergyman, explorer, and botanical researcher | Aizoaceae | Bu |
| Mezia | Carl Christian Mez (1866–1944) | Malpighiaceae | Bu |
| Mezilaurus | Carl Christian Mez (1866–1944) | Lauraceae | Bu |
| Mezzettia | Ignazio Mezzetti (1820–1876), Italian clergyman and teacher of natural science in Lucca und Rome | Annonaceae | Bu |
| Michauxia | André Michaux (1746–1802) | Campanulaceae | St |
| Michelsonia | Alexandr Alexandrovich Michelson or Mikhelson (1907–1973), Russian-born Belgian agricultural engineer and botanist; director of the forestry service | Fabaceae | Bu |
| Micholitzia | Wilhelm Micholitz (1854–1932) | Apocynaceae | Bu |
| Mickelia | John Thomas Mickel (b.1934) American botanist and pteridologist | Dryopteridaceae | Bt |
| Micklethwaitia | John Patrick Micklethwait Brenan (1917–1985) | Fabaceae | Bu |
| Miconia | Francisco Mico (b. 1528), Spanish botanist | Melastomataceae | St |
| Miersia | John Miers (1789–1879) | Amaryllidaceae | Bu |
| Miersiella | John Miers (1789–1879) | Burmanniaceae | Bu |
| Mikania | Joseph Gottfried Mikan (1743–1814) | Asteraceae | St |
| Mikaniopsis | Joseph Gottfried Mikan (1743–1814) | Asteraceae | Bu |
| Mildbraedia | Johannes Mildbraed (1879–1954) | Euphorbiaceae | Bu |
| Mildbraediodendron | Johannes Mildbraed (1879–1954) | Fabaceae | Bu |
| Milicia | Milici (19th and 20th centuries), administrator in Portuguese East Africa (in modern-day Mozambique) who supported the work of the author of the genus, Thomas Robertson Sim | Moraceae | Bu |
| Miliusa | Pierre Bernard Milius (1773–1829), French naval officer; joined the expedition of Nicolas Baudin | Annonaceae | Bu |
| Milla | Julian Milla, gardener to the Spanish king (18th century) | Asparagaceae | St |
| Milleria | Philip Miller (1691–1771) | Asteraceae | Bu |
| Millettia | Charles Millett (1792–1873), English merchant and plant collector; worked for the East India Company in the tea trade | Fabaceae | Ba |
| Milligania | Joseph Milligan (1807–1884), Scottish doctor and botanist, also a geologist; worked as a doctor for the Van Diemen's Land Company | Asteliaceae | Bu |
| Millingtonia | Thomas Millington (1628–1704) | Bignoniaceae | Bu |
| Millotia | possibly Claude-François-Xavier Millot (1726–1785), historian | Asteraceae | Bu |
| Miltonia | Charles Wentworth-Fitzwilliam, 5th Earl Fitzwilliam (1786–1857), Viscount Milton | Orchidaceae | St |
| Miltoniopsis | Charles Wentworth-Fitzwilliam, 5th Earl Fitzwilliam (1786–1857), Viscount Milton | Orchidaceae | Ba |
| Minuartia | Juan Minuart (1693–1768), Spanish botanist | Caryophyllaceae | St |
| Miquelia | Friedrich Anton Wilhelm Miquel (1811–1871) | Icacinaceae | Bu |
| Miqueliopuntia | Friedrich Anton Wilhelm Miquel (1811–1871) | Cactaceae | Bu |
| Mirandea | Faustino Miranda Gonzalez (1905–1964), Spanish-born Mexican botanist | Acanthaceae | Bu |
| Mirbelia | Charles-François Brisseau de Mirbel (1776–1854) | Fabaceae | Bu |
| Misbrookea | Winifred Mary Adelaide Brooke (1894–1975) | Asteraceae | Bu |
| Mitchella | John Mitchell (1711–1768) | Rubiaceae | Co |
| Mnesithea | Mnesitheus (4th century BC), doctor | Poaceae | Bu |
| Mocquerysia | Albert Mocquerys (1860–1926), French dentist; also an entomologist, naturalist and explorer; collected plants and insects in Africa and Venezuela | Salicaceae | Bu |
| Moenchia | Conrad Moench (1744–1805) | Caryophyllaceae | Qu |
| Moldenhawera | Johann Jacob Paul Moldenhawer (1766–1827) | Fabaceae | Bu |
| Molinadendron | José Antonio Molina Rosito (1926–2012) | Hamamelidaceae | Bu |
| Molinaea | Jean Desmoulins or Johannes Molinaeus (1530–1622), French doctor and botanist, student of Jacques Daléchamps and Guillaume Rondelet | Sapindaceae | Bu |
| Molineriella | Ignazio Bernardo Molineri (1741–1818), Italian head gardener at a botanical garden in Turin | Poaceae | Bu |
| Molinia | Juan Ignacio Molina (1740–1829) | Poaceae | Ba |
| Moliniopsis | Juan Ignacio Molina (1740–1829) | Poaceae | Bu |
| Mollia | Karl von Moll (1760–1838) | Malvaceae | Bu |
| Mollinedia | Francisco de Mollinedo (18th century), Spanish naturalist who contributed to a botanical garden in Madrid | Monimiaceae | Bu |
| Moltkia | Joachim Godske Moltke (1746–1818), statesman | Boraginaceae | St |
| Moltkiopsis | Joachim Godske Moltke (1746–1818), statesman | Boraginaceae | Bu |
| Monarda | Nicolás Monardes (c. 1493 – 1588) | Lamiaceae | Co |
| Monardella | Nicolás Monardes (c. 1493 – 1588) | Lamiaceae | St |
| Monimia | Monime (d. 71 BC), noblewoman | Monimiaceae | Bu |
| Monnina | José Moñino, 1st Count of Floridablanca (1728–1808) | Polygalaceae | Bu |
| Monrosia | Francisco de Asis Monrós (1922–1958), Argentinian agricultural engineer who discovered this plant's fruit | Polygalaceae | Bu |
| Monsonia | Lady Anne Monson (1726–1776) | Geraniaceae | St |
| Montanoa | Luis José Ignacio Montaña (1755–1820), Mexican naturalist and physician | Asteraceae | St |
| Monteiroa | Honório da Costa Monteiro Filho (1900–1978), Brazilian professor of botany and director of the national school of agriculture in Rio de Janeiro; specialist in Malvaceae | Malvaceae | Bu |
| Montia | Giuseppe Monti (1682–1760) | Montiaceae | Ch |
| Montinia | Lars Jonasson Montin (1723–1785), Swedish botanist and doctor in Lund and Halland; maintained a large herbarium; student of Carl Linnaeus | Montiniaceae | Bu |
| Montiopsis | Giuseppe Monti (1682–1760) | Montiaceae | Bu |
| Montrichardia | Gabriel de Montrichard, resident of Trinidad; friend of the author of the genus, Hermann Crüger | Araceae | Bu |
| Montrouziera | Xavier Montrouzier (1820–1897) | Clusiaceae | Bu |
| Monttea | Manuel Montt (1809–1880), president of Chile | Plantaginaceae | Bu |
| Moonia | Alexander Moon (1755–1825), Scottish gardener and botanist at Kew Gardens, collected in Gibraltar and North Africa | Asteraceae | Bu |
| Moquinia | Alfred Moquin-Tandon (1804–1863) | Asteraceae | Qu |
| Moquiniastrum | Alfred Moquin-Tandon (1804–1863) | Asteraceae | Bu |
| Moquiniella | Alfred Moquin-Tandon (1804–1863) | Loranthaceae | Qu |
| Moraea | Robert More (1703–1780), English botanist | Iridaceae | St |
| Morangaya | Reid Venable Moran (1916–2010), Edward G. Gay (1916–1997) and Betty Gay (b. 1919) | Cactaceae | Bu |
| Morelia | Morel (d. 1824), French plant collector who died in Senegal | Rubiaceae | Bu |
| Morelotia | Simon Morelot (1751–1809), French apothecary, member and professor at the college of pharmacy | Cyperaceae | Bu |
| Morettia | Giuseppe Moretti (1782–1853) | Brassicaceae | Bu |
| Moricandia | Stefano Moricand (1779–1854) | Brassicaceae | St |
| Moriera | James Justinian Morier (c. 1780 – 1849), diplomat and author | Brassicaceae | Bu |
| Morina | Louis Morin (1635–1715), French botanist | Caprifoliaceae | Co |
| Morisia | Giuseppe Giacinto Moris (1796–1869) | Brassicaceae | St |
| Morisonia | Robert Morison (1620–1683) | Capparaceae | St |
| Morithamnus | Scott Alan Mori | Asteraceae | Bu |
| Moritzia | Alexander Moritzi (1806–1850) | Boraginaceae | Bu |
| Morkillia | William Lucius Morkill (1858–1936), general manager of the Mexican national railroad | Zygophyllaceae | Bu |
| Morronea | Osvaldo Morrone (1957–2011), Argentinian botanist and former director of the Instituto de Botánica Darwinion in San Isidro | Poaceae | Bt |
| Morsacanthus | Walter Baptist Mors (1920–2008), Brazilian chemist who researched useful plants | Acanthaceae | Bu |
| Mortonia | Samuel George Morton (1799–1851) | Celastraceae | Bu |
| Mortoniella | Conrad Vernon Morton (1905–1972) | Apocynaceae | Bu |
| Mortoniodendron | Conrad Vernon Morton (1905–1972) | Malvaceae | Bu |
| Mosannona | Paul Maas (b. 1939) | Annonaceae | Bu |
| Mosiera | Charles A. Mosier (1871–1936), American botanist; a co-writer with the author of the genus, John Kunkel Small | Myrtaceae | Bu |
| Mossia | Charles Edward Moss (1870–1930) | Aizoaceae | Bu |
| Mostuea | Jens Vahl (1796–1854) | Gelsemiaceae | Bu |
| Motherwellia | James Bridgeham Motherwell (c. 1815 – 1886), Irish-born Australian doctor | Araliaceae | Bu |
| Motleyia | James Motley (1822–1859) | Rubiaceae | Bu |
| Motleyothamnus | Timothy 'Tim' J. Motley (1966–2013), American botanist, Professor of Botany at the Old Dominion University and Director of the Botanical Garden in Norfolk, Virginia | Rubiaceae | Bt |
| Moultonianthus | John Coney Moulton (1886–1926) | Euphorbiaceae | Bu |
| Mouretia | Marcellin Mouret (1881–1915), French botanist and soldier in Vietnam and Morocco | Rubiaceae | Bu |
| Moussonia | Albert Mousson (1805–1890) | Gesneriaceae | Bu |
| Muehlbergella | Friedrich Mühlberg (1840–1915) | Campanulaceae | Bu |
| Muehlenbeckia | Heinrich Gustav Mühlenbeck (1798–1845) | Polygonaceae | Co |
| Muellera | Otto Friedrich Müller (1730–1784) | Fabaceae | Bu |
| Muelleranthus | Ferdinand von Mueller (1825–1896) | Fabaceae | Bu |
| Muellerargia | Johannes Müller Argoviensis (1828–1896) | Cucurbitaceae | Bu |
| Muellerina | Ferdinand von Mueller (1825–1896) | Loranthaceae | Bu |
| Muhlenbergia | Gotthilf Heinrich Ernst Muhlenberg (1753–1815) | Poaceae | St |
| Muiria | John Muir (1874–1947) | Aizoaceae | Bu |
| Muiriantha | Thomas Muir (b. 1899), rancher in Western Australia who collected plants and accompanied the author of the genus, Charles Gardner | Rutaceae | Bu |
| Mulguraea | María E. Múlgura (b. 1943), Argentinian botanist; curator and professor at the Instituto de Botánica Darwinion; specialist in Junellia | Verbenaceae | Bu |
| Mullerochloa | Lennox Muller (born 1932), gardener and bamboo importer in Innisfail, Queensland, Australia | Poaceae | Bu |
| Mummenhoffia | Klaus Mummenhoff (b.1956), German botanist, specialist in Brassicaceae and Professor at the Osnabrück University | Brassicaceae | Bt |
| Munnozia | Juan Bautista Muñoz (1745–1799) | Asteraceae | Bu |
| Munroa | William Munro (1818–1880) | Poaceae | Qu |
| Munronia | William Munro (1818–1880) | Meliaceae | Qu |
| Muntingia | Abraham Munting (1626–1683) | Muntingiaceae | Bu |
| Munzothamnus | Philip A. Munz (1892–1974) | Asteraceae | Bu |
| Muraltia | Johannes von Muralt (1645–1733), Swiss botanist and doctor in Zürich, professor of physics | Polygalaceae | Bu |
| Murbeckiella | Svante Samuel Murbeck (1859–1946) | Brassicaceae | Bu |
| Murdannia | Aly Murdann, Indian plant collector; supervised a herbarium in Saharanpur | Commelinaceae | Bu |
| Murraya | Johan Andreas Murray (1740–1791) | Rutaceae | St |
| Muschleria | Reinhold Conrad Muschler (1882–1957) | Asteraceae | Bu |
| Musella | Antonius Musa (63 BC – 14) | Musaceae | Bu |
| Musgravea | Anthony Musgrave (1828–1888), colonial administrator | Proteaceae | Bu |
| Musschia | Jean Henri Mussche (1765–1834), Belgian gardener, curator at a botanical garden in Ghent | Campanulaceae | Bu |
| Mutisia | José Celestino Mutis (1732–1808) | Asteraceae | St |
| Mwasumbia | Leonard B. Mwasumbi (b.1938), Tanzanian botanist, plant taxonomist, specialist in Tanzanian flora, and head of the Herbarium at the University of Dar es Salaam | Annonaceae | Bt |
| Nanuza | Nanuza Luiza de Menezes (b. 1934), Brazilian botanist; curator and professor at the University of São Paulo | Velloziaceae | Bu |
| Napoleonaea | Napoleon (1769–1821), emperor | Lecythidaceae | Bu |
| Nashia | George Valentine Nash (1864–1921) | Verbenaceae | Bu |
| Nassauvia | Karl Heinrich von Nassau-Siegen (1743–1808), naval officer and explorer | Asteraceae | Bu |
| Nathaliella | Nathalie A. Desjatova-Shostenko (1889–1969) | Scrophulariaceae | Bu |
| Naudinia | Charles Victor Naudin (1815–1899) | Rutaceae | Bu |
| Navarretia | Francisco Fernandez de Navarrete (d. 1742), Spanish personal physician and professor of medicine in Granada | Polemoniaceae | Bu |
| Navia | Bernhard Sebastian von Nau (1766–1845), German naturalist, professor of natural history in Mainz; later active as a (political) administrator | Bromeliaceae | Bu |
| Nayariophyton | Madhavan Parameswarau Nayar (1905–1978) | Malvaceae | Bu |
| Nealchornea | Stanesby Alchorne (1727–1800), English botanist at the Chelsea Physic Garden | Euphorbiaceae | Bu |
| Nectouxia | Hippolyte Nectoux (1759–1836), French botanist, botanical garden director in Santo Domingo; head gardener in Fontainebleau; founded a botanical garden in Rome | Solanaceae | Bu |
| Neea | Luis Née (1734–1807) | Nyctaginaceae | Bu |
| Needhamiella | John Needham (1713–1781) | Ericaceae | Bu |
| Neeopsis | Luis Née (1734–1807) | Nyctaginaceae | Bu |
| Neesenbeckia | Christian Gottfried Daniel Nees von Esenbeck (1776–1858) | Cyperaceae | Bu |
| Neesia | Theodor Friedrich Ludwig Nees von Esenbeck (1787–1837) | Malvaceae | Bu |
| Neesiochloa | Christian Gottfried Daniel Nees von Esenbeck (1776–1858) | Poaceae | Bu |
| Negria | Cristoforo Negri (1809–1896) | Gesneriaceae | Bu |
| Neillia | Patrick Neill (1776–1851) | Rosaceae | Co |
| Nelia | Gert Cornelius Nel (1885–1950) | Aizoaceae | Bu |
| Nelmesia | Ernest Nelmes (1895–1959), English botanist, gardener and librarian; worked at Kew Gardens in the herbarium and library; specialist in Carex and Cyperaceae | Cyperaceae | Bu |
| Nelsia | Louis Nels (1855–1910), colonial administrator | Amaranthaceae | Bu |
| Nelsonia | David Nelson (c. 1740 – 1789) | Acanthaceae | Bu |
| Nelsonianthus | Edward William Nelson (1855–1934) | Asteraceae | Bu |
| Neobaclea | César Hipólito Bacle (1794–1838), Swiss naturalist, lithographer and periodicals publisher; collected plants, animals, minerals and cultural materials in South America and elsewhere | Malvaceae | Bu |
| Neobassia | Ferdinando Bassi (1710–1774), Italian botanist | Amaranthaceae | Bu |
| Neobathiea | Joseph Marie Henry Alfred Perrier de la Bâthie (1873–1958) | Orchidaceae | Bu |
| Neobeguea | Louis Henri Bégué (1906–1979), French civil servant in the forestry service in Madagascar | Meliaceae | Bu |
| Neobertiera | Bertier, a French Guianese woman who helped Jean Baptiste Christophore Fusée Aublet with native plants, including this genus, found on her property | Rubiaceae | Bu |
| Neoblakea | Sidney Fay Blake (1892–1959) | Rubiaceae | Qu |
| Neobolusia | Harry Bolus (1834–1911) | Orchidaceae | Bu |
| Neobouteloua | Claudio Boutelou (1774–1842), Spanish gardener and botanist, and his brother Esteban Boutelou (1776–1813), botanist and agronomist | Poaceae | Bu |
| Neoboutonia | Louis Bouton (1800–1878), French-Mauritian botanist in Port Louis, Mauritius | Euphorbiaceae | Bu |
| Neobracea | Lewis Jones Knight Brace (1852–1938), English botanist; collected plants in the Bahamas; worked at a botanical garden in Kolkata in West Bengal | Apocynaceae | Bu |
| Neobrittonia | Nathaniel Lord Britton (1859–1934) | Malvaceae | Bu |
| Neobuchia | Wilhelm Buch (1862–1943), German pharmacist and botanist, and his wife Amalia Pauline Wilhelmine Buch (c. 1867–1900) | Malvaceae | Bu |
| Neochevalierodendron | Auguste Chevalier (1873–1956) | Fabaceae | Bu |
| Neocogniauxia | Alfred Cogniaux (1841–1916) | Orchidaceae | Bu |
| Neocollettia | Henry Collett (1836–1901) | Fabaceae | Bu |
| Neocuatrecasia | José Cuatrecasas (1903–1996) | Asteraceae | Bu |
| Neocussonia | Pierre Cusson (1727–1783) | Araliaceae | Bu |
| Neodillenia | Johann Jacob Dillenius (1684–1747) | Dilleniaceae | Bu |
| Neodriessenia | Peter van Driessen (1753–1828), Dutch doctor, pharmacist, chemist and botanist; professor of medicine in Harderwijk und Groningen | Melastomataceae | Bu |
| Neofabricia | Philipp Conrad Fabricius (1714–1774), German doctor and professor of botany in Helmstedt | Myrtaceae | Bu |
| Neogardneria | George Gardner (1810–1849) | Orchidaceae | Bu |
| Neogaya | Jaques Étienne Gay (1786–1864) | Apiaceae | Bu |
| Neoglaziovia | Auguste François Marie Glaziou (1828–1906) | Bromeliaceae | St |
| Neogoezia | Edmund Goeze (1838–1929), German gardener and botanist; botanical museum director in Coimbra, Portugal; botanical garden inspector in Greifswald | Apiaceae | Bu |
| Neogontscharovia | Nikolái Gontscharow (1900–1942), Russian botanist and collector | Plumbaginaceae | Bu |
| Neoguillauminia | André Guillaumin (1885–1974) | Euphorbiaceae | Bu |
| Neoharmsia | Hermann Harms (1870–1942) | Fabaceae | Bu |
| Neohemsleya | James Hatton Hemsley (b. 1923), English botanist at Kew Gardens; specialist in African Sapotaceae | Sapotaceae | Bu |
| Neohenricia | Margaret Gertrude Anna Henrici (1892–1971), Swiss-born South African botanist and physiologist | Aizoaceae | Bu |
| Neoholmgrenia | Patricia Kern Holmgren (b. 1940), Noel Herman Holmgren (b. 1937), and Arthur Herman Holmgren (1912–1992) | Onagraceae | Bu |
| Neohouzeaua | Jean Houzeau de Lehaie (1867–1959), | (Poaceae | Bt |
| Neojeffreya | Charles Jeffrey (b. 1934), English botanist at Kew Gardens and in Saint Petersburg in Russia; specialist in Asteraceae and Cucurbitaceae | Asteraceae | Bu |
| Neojobertia | Clément Léger Nicolas Jobert (1840–1910), plant collector in Brazil | Bignoniaceae | Bu |
| Neokochia | Wilhelm Daniel Joseph Koch (1771–1849), German doctor and botanist; professor of medicine and botany in Erlangen, and botanical garden director there | Amaranthaceae | Bu |
| Neolamarckia | Jean-Baptiste Lamarck (1744–1829) | Rubiaceae | Bu |
| Neolemonniera | George Le Monnier (1843–1931), French botanist and mycologist; professor of botany in Nancy | Sapotaceae | Bu |
| Neolloydia | Francis Ernest Lloyd (1868–1947) | Cactaceae | St |
| Neoluederitzia | Franz Adolf Eduard Lüderitz (1834–1896), German merchant involved in the creation of German South West Africa (now Namibia); namesake of Lüderitz Bay | Zygophyllaceae | Qu |
| Neomezia | Carl Christian Mez (1866–1944) | Primulaceae | Bu |
| Neomillspaughia | Charles Frederick Millspaugh (1854–1923), American doctor and botanist; professor of medical botany in Chicago | Polygonaceae | Bu |
| Neomirandea | Faustino Miranda Gonzalez (1905–1964), Spanish-born Mexican botanist | Asteraceae | Bu |
| Neomoorea | Frederick William Moore (1857–1949) | Orchidaceae | Bu |
| Neomortonia | Conrad Vernon Morton (1905–1972) | Gesneriaceae | Bu |
| Neonelsonia | Edward William Nelson (1855–1934) | Apiaceae | Bu |
| Neonicholsonia | George Nicholson (1847–1908) | Arecaceae | Bu |
| Neonotonia | Benjamin Noton (1784–1869), English mint director in present-day Mumbai with an interest in natural science; collected in southern India | Fabaceae | Bu |
| Neopallasia | Peter Simon Pallas (1741–1811) | Asteraceae | Bu |
| Neoparrya | Charles Christopher Parry (1823–1890) | Apiaceae | Bu |
| Neopringlea | Cyrus Pringle (1838–1911) | Salicaceae | Bu |
| Neoraimondia | Antonio Raimondi (1826–1890) | Cactaceae | Bu |
| Neorautanenia | Martti Rautanen (1845–1926) | Fabaceae | Bu |
| Neoregelia | Eduard August von Regel (1815–1892) | Bromeliaceae | St |
| Neoregnellia | Anders Fredrik Regnell (1807–1884) | Malvaceae | Bu |
| Neoroepera | Johannes August Christian Roeper (1801–1885), German doctor and botanist; professor of botany in Basel and in Rostock; later also the university librarian at Rostock | Picrodendraceae | Bu |
| Neorudolphia | Karl Rudolphi (1771–1832) | Fabaceae | Bu |
| Neoschmidia | Maurice Schmid (1922–2018), French botanist in Africa, Southeast Asia and New Caledonia; specialist in the flora of New Caledonia; then at the National Museum of Natural History in Paris | Rutaceae | Bu |
| Neoschumannia | Karl Moritz Schumann (1851–1904) | Apocynaceae | Bu |
| Neoscortechinia | Benedetto Scortechini (1845–1886) | Euphorbiaceae | Bu |
| Neosprucea | Richard Spruce (1817–1893) | Salicaceae | Bu |
| Neostapfia | Otto Stapf (1857–1933) | Poaceae | Bu |
| Neostapfiella | Otto Stapf (1857–1933) | Poaceae | Bu |
| Neotatea | George Henry Hamilton Tate (1894–1953) | Bonnetiaceae | Bu |
| Neotessmannia | Günther Tessmann (1884–1969), German-Brazilian ethnologist and botanist; explorer and plant collector in western tropical Africa; worked at the Paranaense Museum in Curitiba | Muntingiaceae | Bu |
| Neothorelia | Clovis Thorel (1833–1911) | Capparaceae | Bu |
| Neotinea | Vincenzo Tineo (1791–1856) | Orchidaceae | Bu |
| Neotysonia | Isaac Tyson (1859–1942), plant collector in Western Australia | Asteraceae | Bu |
| Neoveitchia | John Veitch (1752–1839) | Arecaceae | Bu |
| Neowerdermannia | Erich Werdermann (1892–1959) | Cactaceae | Bu |
| Nepsera | Fridolin Karl Leopold Spenner (1798–1841), German doctor and botanist; director of the university botanical garden in Freiburg and professor of medical botany there | Melastomataceae | Bu |
| Neraudia | Jules Néraud (1794–1855) | Urticaceae | Bu |
| Nernstia | Walther Hermann Nernst (1864–1941), German chemist | Rubiaceae | Bt |
| Neslia | Jacques Amable Nicolas Denesle (1735–1819), French botanist in Liège und Caen; later a teacher of natural science and a botanical garden director in Poitiers | Brassicaceae | Bu |
| Nesomia | Guy L. Nesom (b. 1945) | Asteraceae | Bu |
| Nestlera | Chrétien Géofroy Nestler (1778–1832) | Asteraceae | Qu |
| Neuburgia | Christophorus (Christoffel) Thun von Neuburg (Thum-Neuburg); built up a botanical garden in Swabia in Germany | Loganiaceae | Bu |
| Neuwiedia | Prince Maximilian of Wied-Neuwied (1782–1867) | Orchidaceae | Bu |
| Nevillea | Neville Stuart Pillans (1884–1964), South African botanist at the Bolus Herbarium in Cape Town | Restionaceae | Bu |
| Neviusia | Ruben Denton Nevius (1827–1913), the plant's discoverer | Rosaceae | St |
| Newbouldia | William Williamson Newbould (1819–1886), British clergyman in Kew and elsewhere; also a botanist and collector | Bignoniaceae | Bu |
| Newcastelia | Henry Pelham-Clinton, 5th Duke of Newcastle (1811–1864) | Lamiaceae | Bu |
| Newmania | Mark Fleming Newman (b. 1959), British botanist at a botanical garden in Edinburgh, specialist in Zingiberaceae | Zingiberaceae | Bu |
| Newtonia | Isaac Newton (1642–1727) | Fabaceae | Bu |
| Neyraudia | Auguste Adolphe Marc Reynaud (1804–1867) | Poaceae | Bu |
| Nicandra | Nicander | Loganiaceae | Co |
| Nichallea | Nicolas Hallé, French botanist at the National Museum of Natural History; specialist in Rubiaceae | Rubiaceae | Bu |
| Nicolasia | N. E. Brown (1849–1934) | Asteraceae | Bu |
| Nicolletia | Joseph Nicollet (1786–1843) | Asteraceae | Bu |
| Nicotiana | Jean Nicot (1530–1604), diplomat | Solanaceae | Co |
| Niedenzuella | Franz Josef Niedenzu (1857–1937) | Malpighiaceae | Bu |
| Niemeyera | Felix von Niemeyer (1820–1871), doctor | Sapotaceae | Bu |
| Nierembergia | Juan Eusebio Nieremberg (1595–1658) | Solanaceae | Co |
| Nietneria | Eduard I. Nietner (1796–1859), German royal court gardener in Berlin and Potsdam; took a position at the royal institute for gardening education | Nartheciaceae | Bu |
| Nissolia | Guillaume Nissole (1647–1735), French botanist, historian of science and doctor in Montpellier; identified plants for the French Academy of Sciences in Paris and Montpellier | Fabaceae | Bu |
| Nivellea | Robert Nivelle (1856–1924), military officer | Asteraceae | Bu |
| Nivenia | James Niven (1774–1826), Scottish botanist | Iridaceae | St |
| Noaea | François Thomas "Frank", Marquis De Noé (1806–1887) French author on North African Lamiaceae | Amaranthaceae | Bu |
| Noccaea | Domenico Nocca (1758–1841), Italian clergyman and botanist; director of botanical gardens in Mantua and Pavia; professor of botany in Pavia | Brassicaceae | Bu |
| Noccaeopsis | Domenico Nocca (1758–1841), Italian clergyman and botanist; director of botanical gardens in Mantua and Pavia; professor of botany in Pavia | Brassicaceae | Bu |
| Nohawilliamsia | Norris Hagan Williams (b. 1943), American botanist, specialist in orchids; curator and professor of botany at the Florida Museum of Natural History | Orchidaceae | Bu |
| Noisettia | Louis Claude Noisette (1772–1849) | Violaceae | Bu |
| Nolina | Abbé Pierre Charles Nolin (1717–1795), French botanist and writer | Asparagaceae | St |
| Nolletia | Jean-Antoine Nollet (1700–1770), physicist | Asteraceae | Bu |
| Noltea | Ernst Ferdinand Nolte (1791–1875) | Rhamnaceae | St |
| Nonea | Johann Philipp Nonne (1729–1772), German doctor and botanist; professor of medicine in Erfurt | Boraginaceae | Bu |
| Nordenstamia | Bertil Nordenstam (b. 1936) | Asteraceae | Bu |
| Normanbya | George Phipps, 2nd Marquess of Normanby (1819–1890) | Arecaceae | Bu |
| Normandia | Sébastien René Lenormand (1796–1871) | Rubiaceae | Bu |
| Normeyera | Norbert Meyer (1954– ), German botanist, specialist in Sorbus in central Europe and curator of the Herbarium at Natural History Museum in Nürnberg | Rosaceae | Bt |
| Normandiodendron | Didier Normand (1908–2002), research director for tropical forests in Nogent-sur-Marne, France; specialist in tropical wood | Fabaceae | Bu |
| Noronhia | Francisco Noronha (c. 1748 – 1788) | Oleaceae | Bu |
| Norrisia | William Norris (1793–1859), judge and justice | Loganiaceae | Bu |
| Northia | Marianne North (1830–1890) | Sapotaceae | Bu |
| Nouelia | André Edmé Nouel (1801–1887), French mathematician and scientist at the Collège royal in Orléans; director of the natural history museum there | Asteraceae | Bu |
| Nouhuysia | Jan Willem van Nouhuys (1869–1963), Dutch naval officer and seafarer; collected plants in New Guinea; director at two museums in Rotterdam | Clusiaceae | Bu |
| Noveloa | Luis Alejandro Novelo Retana (1951–2006), Mexican botanist at the University of Mexico; specialist in native aquatic plants and Podostemaceae of the neotropics | Podostemaceae | Bu |
| Nowickea | Joan W. Nowicke (b. 1938) | Phytolaccaceae | Qu |
| Nuttallanthus | Thomas Nuttall (1786–1859) | Plantaginaceae | Bu |
| Nuxia | Jean Baptiste François de Lanux (1702–1772), French amateur botanist on Réunion | Stilbaceae | Bu |
| Nuytsia | Pieter Nuyts (1598–1655) | Loranthaceae | Bu |
| Nymania | Carl Fredrik Nyman (1820–1893) | Meliaceae | Bu |
| Obetia | possibly Arthur Obet (1802–1842) or Louis Jean Marie Obet (1777–1856), both French naval surgeons | Urticaceae | Bu |
| Obregonia | Álvaro Obregón (1880–1928), president of Mexico | Cactaceae | Ba |
| Ochagavia | Silvestre Ochagavía Errázuriz (b. 1820), Chilean minister of education | Bromeliaceae | St |
| Ochoterenaea | Isaac Ochoterena (1885–1950), Mexican botanist and histologist; taught at the University of Mexico | Anacardiaceae | Bu |
| Oddoniodendron | Adolf Oddon (1863–1906), Belgian clergyman in Namur and Liège; collected plants in Africa for a botanical garden in Brussels | Fabaceae | Bu |
| Odonellia | Carlos Alberto O'Donell (1912–1954), Argentinian botanist at the Miguel Lillo Foundation in San Miguel de Tucumán | Convolvulaceae | Bu |
| Oedera | Georg Christian Oeder (1728–1791) | Asteraceae | Bu |
| Oemleria | Augustus Gottlieb Oemler (1773–1852), German-American naturalist | Rosaceae | Co |
| Oestlundia | Karl Erik Magnus Östlund (1875–1938), Swedish plant collector; collected orchids in Mexico | Orchidaceae | Bu |
| Ohwia | Jisaburo Ohwi (1905–1977) | Fabaceae | Bu |
| Okenia | Lorenz Oken (1779–1851) | Nyctaginaceae | Bu |
| Oldenburgia | Franz Pehr Oldenburg (1740–1774), Swedish plant collector; traveled as a soldier in the service of the Danish East India Company to South Africa and Madagascar; collected for Kew Gardens | Asteraceae | Bu |
| Oldenlandia | Henrik Bernard Oldenland (1663–1697) | Rubiaceae | Bu |
| Oldenlandiopsis | Henrik Bernard Oldenland (1663–1697) | Rubiaceae | Bu |
| Oldfeltia | Karin Oldfelt Hjertonsson (b. 1940), Swedish artist who collaborated with the author Bertil Nordenstam; was the Swedish ambassador to Cuba for several years | Asteraceae | Bu |
| Oldfieldia | Richard Albert Kearns Oldfield (1809–1859), British doctor and colonial administrator | Picrodendraceae | Bu |
| Olearia | Johann Gottfried Olearius (1635–1711), German theologian | Asteraceae | Co |
| Olfersia | Ignaz Franz Werner Maria von Olfers, (1793–1871) | Dryopteridaceae | Bt |
| Olgaea | Olga Fedchenko (1845–1921) | Asteraceae | Bu |
| Olinia | Johan Henrik Olin (1769–1824), Swedish student of Carl Peter Thunberg | Penaeaceae | St |
| Oliverella | Daniel Oliver (1830–1916) | Loranthaceae | Bu |
| Oliveria | Guillaume-Antoine Olivier (1756–1814) | Apiaceae | Bu |
| Oliveriana | Daniel Oliver (1830–1916) | Orchidaceae | Bu |
| Olmediella | Vicente de Olmedo (c. 1763 – 1854), botanist and royal warden of Cinchona groves (for quinine) | Salicaceae | Bu |
| Olneya | Stephen Thayer Olney (1812–1878) | Fabaceae | Bu |
| Ooia | Ooi Im Hin, student of the authors of the genus, Sin Yeng Wong and Peter Charles Boyce | Araceae | Bu |
| Orania | William I of the Netherlands (1772–1843) | Arecaceae | Bu |
| Oraniopsis | William I of the Netherlands (1772–1843) | Arecaceae | Bu |
| Orcuttia | Charles Russell Orcutt (1864–1929) | Poaceae | Qu |
| Oreomunnea | Francisco María Oreamuno Bonilla (1801–1856), politician | Juglandaceae | Bu |
| Oreoschimperella | Georg Wilhelm Schimper (1804–1878) | Apiaceae | Bu |
| Orfilea | Mathieu Orfila (1787–1853), toxicologist | Euphorbiaceae | Bu |
| Orlaya | János Orlay (1770–1829), Hungarian theologist and doctor; military doctor in Russian service | Apiaceae | Ba |
| Orleanesia | Prince Gaston, Count of Eu (1842–1922) | Orchidaceae | Bu |
| Ornduffia | Robert Ornduff (1932–2000) | Menyanthaceae | Bu |
| Ortegia | José Ortega (d. 1761), Spanish military apothecary at the court of Ferdinand VI; secretary of the royal academy of medicine; director of a medicinal botanical garden in Madrid | Caryophyllaceae | Bu |
| Ortegocactus | Francisco Ortega (20th century), plant collector, and his extended family from San José Lachiguiri in Mexico | Cactaceae | Ba |
| Orthopichonia | Marcel Pichon (1921–1954) | Apocynaceae | Bu |
| Osbeckia | Pehr Osbeck (1723–1805) | Melastomataceae | St |
| Osbertia | Osbert Salvin (1835–1898) | Asteraceae | Bu |
| Osbornia | John Walter Osborne (1828–1902), chemist | Myrtaceae | Bu |
| Oschatzia | Adolph Oschatz (1812–1857), German doctor and botanist; an inventor of microtomy | Apiaceae | Bu |
| Oserya | Alexandre Victor Eugène Hulot d'Osery (1819–1846), French geologist and engineer | Podostemaceae | Bu |
| Ossaea | José Antonio de la Ossa (d. c. 1829), Cuban botanist; botanical garden director in Havana | Melastomataceae | Bu |
| Ostrowskia | Michael Nicholazewitsch von Ostrowsky (1827–1901), Russian minister of the interior | Campanulaceae | St |
| Osvaldoa | Osvaldo Morrone (1957–2011), Argentinian botanist and former director of the Instituto de Botánica Darwinion in San Isidro | Poaceae | Bt |
| Oteiza | Juan José de Oteiza y Vértiz (1777–1810), Mexican clergyman and natural scientist; professor of physics and mineralogy | Asteraceae | Bu |
| Ottleya | Alice Maria Ottley (1882–1971) | Fabaceae | Bu |
| Ottoa | Christoph Friedrich Otto (1783–1856) | Apiaceae | Bu |
| Ottochloa | Otto Stapf (1857–1933) | Poaceae | Bu |
| Ottoschmidtia | Otto Christian Schmidt (1900–1951), German botanist, professor in Berlin und Münster; specialist in algae | Rubiaceae | Bu |
| Ottoschulzia | Otto Eugen Schulz (1874–1936) | Metteniusaceae | Bu |
| Ottosonderia | Otto Wilhelm Sonder (1812–1881) | Aizoaceae | Bu |
| Ourisia | Oury, governor of the Falkland Islands in the 1760s | Plantaginaceae | St |
| Ovidia | Ovid (43 BC – c. 17), poet | Thymelaeaceae | Bu |
| Ovieda | Gonzalo Fernández de Oviedo y Valdés (1478–1557), colonialist and historian | Lamiaceae | Bu |
| Owenia | Richard Owen (1804–1892) | Meliaceae | Bu |
| Oyedaea | Alfonso Oyeda, Spanish seafarer; brought Amerigo Vespucci to the New World | Asteraceae | Bu |
| Pabstia | Guido Frederico João Pabst (1914–1980) | Orchidaceae | Bu |
| Pabstiella | Guido Frederico João Pabst (1914–1980) | Orchidaceae | Bu |
| Packera | John G. Packer (1929–2019), Canadian botanist at the university in Alberta, specialist in Albertan, alpine and arctic flora | Asteraceae | Ba |
| Padbruggea | Robbert Padtbrugge (1638–1703), Dutch doctor in the service of the Dutch East India Company; governor of Ternate | Fabaceae | Bu |
| Painteria | Joseph Hannum Painter (1879–1908), American plant collector; collected with the author of the genus, Joseph Nelson Rose | Fabaceae | Bu |
| Palafoxia | perhaps José de Palafox y Melci (1776–1847), military officer, or Juan de Palafox y Mendoza (1600–1659), bishop and politician | Asteraceae | St |
| Palaua | Antonio Palau y Verdera (1734–1793), Spanish naturalist | Malvaceae | St |
| Palisota | Palisot de Beauvois (1752–1820) | Commelinaceae | St |
| Palmerella | Edward Palmer (c. 1829 – 1911) | Campanulaceae | Qu |
| Palmeria | James Frederick Palmer (1803–1871), doctor and politician | Monimiaceae | Qu |
| Pamianthe | Albert Pam (1875–1955), financier and Fellow of the Linnean Society | Amaryllidaceae | St |
| Pancheria | Jean Armand Isidore Pancher (1814–1877) | Cunoniaceae | Bu |
| Panda | Paul Panda Farnana (1888–1930) | Pandaceae | Ch |
| Paneroa | José L. Panero (b. 1959), American botanist from University of Texas in Austin | Asteraceae | Bt |
| Panzerina | Georg Wolfgang Franz Panzer (1755–1829) | Lamiaceae | Bu |
| Pappea | Karl Wilhelm Ludwig Pappe (1803–1862) | Sapindaceae | Bu |
| Paradisea | Giovanni Paradisi (1760–1826), mathematician, writer and senator | Asparagaceae | Co |
| Parishia | Charles Samuel Pollock Parish (1822–1897), Indian-born English clergyman and botanist, missionary in Burma (present-day Myanmar); collected mosses and orchids | Anacardiaceae | Bu |
| Parkia | Mungo Park (1771–1806) | Fabaceae | Bu |
| Parkinsonia | John Parkinson (1567–1650) | Fabaceae | St |
| Parlatoria | Filippo Parlatore (1816–1877) | Brassicaceae | Bu |
| Parmentiera | Antoine-Augustin Parmentier (1737–1813) | Bignoniaceae | St |
| Parodia | Domingo Parodi (1823–1890) | Cactaceae | Qu |
| Parodianthus | Lorenzo Raimundo Parodi (1895–1966), Argentinian botanist and agricultural engineer, professor of botany in Buenos Aires and La Plata with a focus on South American grasses | Verbenaceae | Bu |
| Parodiodendron | Lorenzo Raimundo Parodi (1895–1966), Argentinian botanist and agricultural engineer, professor of botany in Buenos Aires and La Plata with a focus on South American grasses | Picrodendraceae | Bu |
| Parodiodoxa | Lorenzo Raimundo Parodi (1895–1966), Argentinian botanist and agricultural engineer, professor of botany in Buenos Aires and La Plata with a focus on South American grasses | Brassicaceae | Bu |
| Parodiophyllochloa | Lorenzo Raimundo Parodi (1895–1966), Argentinian botanist and agricultural engineer, professor of botany in Buenos Aires and La Plata with a focus on South American grasses | Poaceae | Bu |
| Parolinia | Alberto Parolini (1788–1867), Italian botanist from Bassano del Grappa; student of Giovanni Battista Brocchi | Brassicaceae | Bu |
| Parrotia | Friedrich Parrot (1792–1841) | Hamamelidaceae | Co |
| Parrotiopsis | Friedrich Parrot (1792–1841) | Hamamelidaceae | St |
| Parrya | William Edward Parry (1790–1855), naval officer and explorer | Brassicaceae | Bu |
| Parryella | Charles Christopher Parry (1823–1890) | Fabaceae | Bu |
| Parsana | Ahmad Parsa (1907–1997) | Urticaceae | Bu |
| Parsonsia | James Parsons (1705–1770), doctor and antiquary | Apocynaceae | Bu |
| Pasaccardoa | Pier Andrea Saccardo (1845–1920) | Asteraceae | Bu |
| Pascalia | Diego Baldassare Pascal (1768–1812), French-born Italian doctor and botanist; professor of botany in Parma and botanical garden director | Asteraceae | Bu |
| Passovia | Friedrich Passow (19th century), German consul in Puerto Cabello in Venezuela; member of Rostock's naturalist society | Loranthaceae | Bu |
| Patersonia | William Paterson (1755–1810) | Iridaceae | Ba |
| Patinoa | Víctor Manuel Patiño (1912–2001), Colombian agricultural technologist | Malvaceae | Bu |
| Patrinia | Eugène Louis Melchior Patrin (1742–1814) | Caprifoliaceae | Co |
| Patzkea | Erwin Patzke (1929–2018), German botanist and professor, specialist in grasses | Poaceae | Bu |
| Pauia | Hermenegild Santapau (1903–1970) | Solanaceae | Bu |
| Pauldopia | Paul Louis Amans Dop (1876–1954) | Bignoniaceae | Bu |
| Paulita | (Paul) Pavel Nikolaevich Ovczinnikov (1903–1979), Russian Botanist | Apiaceae | Bt |
| Paullinia | Simon Paulli (1603–1680) | Sapindaceae | St |
| Paulownia | Anna Pavlovna of Russia (1795–1865) | Paulowniaceae | Ch |
| Pavonia | José Antonio Pavón Jiménez (1754–1844) | Malvaceae | St |
| Payena | Anselme Payen (1795–1871) | Sapotaceae | Bu |
| Payera | Jean-Baptiste Payer (1818–1860), French doctor, botanist (bryologist) and naturalist; professor of geology and mineralogy at the university in Rennes | Rubiaceae | Bu |
| Paysonia | Edwin Blake Payson (1893–1927), American botanist, specialist in Lesquerella | Brassicaceae | Bu |
| Pearcea | Richard Pearce (c. 1835 – 1868) | Gesneriaceae | Bu |
| Pearsonia | Henry Harold Welch Pearson (1870–1916) | Fabaceae | Bu |
| Pechuel-loeschea | Eduard Pechuël-Loesche (1840–1913) | Asteraceae | Bu |
| Peddiea | John Peddie (d. 1840), British military officer and plant collector; fought in South Africa and elsewhere; namesake of Fort Peddie there | Thymelaeaceae | Bu |
| Pedersenia | Troels Myndel Pedersen (1916–2000), Danish-born Argentinian botanist with a large herbarium; specialist in Amaranthaceae | Amaranthaceae | Bu |
| Pedleya | Leslie Pedley (1930–2018), was an Australian botanist who specialised in the genus Acacia | Fabaceae | Bt |
| Peersia | Victor Stanley Peers (1874–1940), Australian botanist, plant collector, and amateur archeologist | Aizoaceae | Qu |
| Pegolettia | Francesco Balducci Pegolotti (fl. 1310 – 1347), merchant | Asteraceae | Bu |
| Pehria | Pehr Löfling (1729–1756) | Lythraceae | Bu |
| Peixotoa | Domingos Ribeiro II (1790–1846), Brazilian personal physician at the Brazilian court in Rio de Janeiro | Malpighiaceae | Bu |
| Pellegrinia | François Pellegrin (1881–1965) | Ericaceae | Bu |
| Pelliciera | Guillaume Pellicier (1490–1568) | Tetrameristaceae | Bu |
| Pellionia | Marie Joseph Alphonse Pellion (1796–1868), French naval officer (later an admiral); took part in a global expedition on the ship Uranie | Urticaceae | Ba |
| Pembertonia | Pemberton Walcott (1834–1883), English plant collector who settled in Western Australia; namesake of the city Pemberton | Asteraceae | Bu |
| Penaea | Pierre Pena (1535–1605), French doctor and botanist; assistant to Matthias de l'Obel in Montpellier and in England; also a royal personal physician | Penaeaceae | Bu |
| Pennantia | Thomas Pennant (1726–1798) | Pennantiaceae | Bu |
| Pennellia | Francis W. Pennell (1886–1952) | Brassicaceae | Bu |
| Pennellianthus | Francis W. Pennell (1886–1952) | Plantaginaceae | Bu |
| Pentzia | Carl Johann or Carolus Johannes Pentz (18th and 19th centuries), Swedish student of Carl Peter Thunberg | Asteraceae | Bu |
| Pereskia | Nicolas-Claude Fabri de Peiresc (1580–1637) | Cactaceae | St |
| Pereskiopsis | Nicolas-Claude Fabri de Peiresc (1580–1637) | Cactaceae | St |
| Perezia | Lorenzo or Lázaro Perez, 16th-century Spanish apothecary and author | Asteraceae | St |
| Periandra | Periander (627 BC – 584 BC), ruler | Fabaceae | Bu |
| Periclesia | Pericles (c. 490 BC – 429 BC), statesman | Ericaceae | Bu |
| Perralderia | Henri René Letourneux de la Perraudière (1831–1861), French botanist who collected in France and Algeria and on the islands of Madeira and the Canaries | Asteraceae | Bu |
| Perriera | Joseph Marie Henry Alfred Perrier de la Bâthie (1873–1958) | Simaroubaceae | Bu |
| Perrierbambus | Joseph Marie Henry Alfred Perrier de la Bâthie (1873–1958) | Poaceae | Bu |
| Perrierodendron | Joseph Marie Henry Alfred Perrier de la Bâthie (1873–1958) | Sarcolaenaceae | Bu |
| Perrierophytum | Joseph Marie Henry Alfred Perrier de la Bâthie (1873–1958) | Malvaceae | Bu |
| Perrierosedum | Joseph Marie Henry Alfred Perrier de la Bâthie (1873–1958) | Crassulaceae | Bu |
| Perrottetia | George Samuel Perrottet (1793–1870) | Dipentodontaceae | Bu |
| Perryodendron | Lily May Perry (1895–1992) | Rutaceae | Bu |
| Persoonia | Christiaan Hendrik Persoon (1761–1836) | Proteaceae | St |
| Pertya | Maximilian Perty (1804–1884) | Asteraceae | Bu |
| Pervillaea | Auguste Pervillé (d. c. 1868), French botanist at the National Museum of Natural History; collected on Réunion, Madagascar and neighboring islands | Apocynaceae | Bu |
| Pescatoria | Jean-Pierre Pescatore (1793–1865), merchant and orchid enthusiast | Orchidaceae | St |
| Petagnaea | Vincenzo Petagna (1734–1810) | Apiaceae | Bu |
| Petchia | Tom Petch (1870–1948) | Apocynaceae | Bu |
| Petelotiella | Paul Alfred Pételot (1885–1965) | Urticaceae | Bu |
| Peteravenia | Peter H. Raven (b. 1936) | Asteraceae | Bu |
| Peteria | Robert Peter (1805–1894), English-born American botanist, chemist, doctor, zoologist and geologist; founder of the University of Louisville School of Medicine | Fabaceae | Bu |
| Petermannia | August Heinrich Petermann (1822–1878) | Petermanniaceae | Bu |
| Peterodendron | Gustav Albert Peter (1853–1937) | Achariaceae | Bu |
| Petersianthus | Wilhelm Peters (1815–1883) | Lecythidaceae | Bu |
| Petiniotia | Richard Petiniot (d. before 1980), Belgian air force officer in the Sahara and Iran | Brassicaceae | Bu |
| Petitia | François Pourfour du Petit (1664–1741), doctor | Lamiaceae | Qu |
| Petitiocodon | Ernest Marie Antoine Petit (1927–2007), Belgian professor of botany and botanical garden director | Rubiaceae | Bu |
| Petiveria | James Petiver (c. 1660 – 1718) | Petiveriaceae | Ch |
| Petrea | Robert Petre, 8th Baron Petre (1713–1742) | Verbenaceae | St |
| Petroedmondia | Pierre Edmond Boissier (1810–1885) | Apiaceae | Bu |
| Petrosavia | Pietro Savi (1811–1871), Italian professor of botany in Pisa; botanical garden director | Petrosaviaceae | Bu |
| Petrosimonia | Peter Simon Pallas (1741–1811) | Amaranthaceae | Bu |
| Petteria | Franz Petter (1798–1853), Austrian botanist in Dalmatia | Fabaceae | St |
| Peyritschia | Johann Joseph Peyritsch (1835–1889) | Poaceae | Bu |
| Pfaffia | Christoph Heinrich Pfaff (1773–1852) | Amaranthaceae | Bu |
| Pfeiffera | Ludwig Karl Georg Pfeiffer (1805–1877) | Cactaceae | Bu |
| Phania | Phaenias of Eresus (4th century BC), philosopher | Asteraceae | Bu |
| Pharnaceum | Pharnaces II of Pontus (died 47 BC) | Molluginaceae | Bu |
| Phelpsiella | William H. Phelps Sr. (1875–1965) and his son William H. Phelps Jr. (1902–1988) and daughter-in-law Katherine Deery Phelps (1908–2001) | Rapateaceae | Bu |
| Phelypaea | Louis Phélypeaux, comte de Pontchartrain (1643–1727) and Jérôme Phélypeaux (1674–1747), politician | Orobanchaceae | Bu |
| Philadelphus | perhaps Ptolemy II Philadelphus (c. 308 BC – 246 BC) | Hydrangeaceae | Co |
| Philcoxia | David Philcox (1926–2003), English botanist at Kew Gardens who worked extensively in tropical Scrophulariaceae | Plantaginaceae | Bt |
| Philibertia | Jean-Baptiste-Charles Legendre de Luçay (1754–1836), French administrator and landowner; wrote an introduction to botany and a botanical dictionary | Apocynaceae | Bu |
| Philippiella | Rodolfo Amando Philippi (1808–1904) | Caryophyllaceae | Bu |
| Phippsia | Constantine Phipps, 2nd Baron Mulgrave (1744–1792) | Poaceae | Bu |
| Phitosia | Dimitrios Phitos (b. 1930), Greek professor of botany at the university in Patras; specialist in Greek flora | Asteraceae | Bu |
| Picardaea | Louis Picarda (1848–1901), French clergyman, professor of natural science, natural history and botany on Martinique | Rubiaceae | Bu |
| Picconia | Giovanni Maria Piccone (1772–1832), Italian clergyman and agronomist, member of various scientific societies in Italy and in Paris | Oleaceae | Bu |
| Pichonia | Louis Auguste Pichon (1838–1924), French naval doctor, consul in Shanhai, China | Sapotaceae | Bu |
| Pickeringia | Charles Pickering (1805–1878) | Fabaceae | Bu |
| Pictetia | Marc-Auguste Pictet (1752–1825) | Fabaceae | Bu |
| Pierranthus | Jean Baptiste Louis Pierre (1833–1905) | Linderniaceae | Bu |
| Pierreodendron | Jean Baptiste Louis Pierre (1833–1905) | Simaroubaceae | Bu |
| Pierrina | Jean Baptiste Louis Pierre (1833–1905) | Lecythidaceae | Bu |
| Pigafetta | Antonio Pigafetta (c. 1491 – c. 1531), explorer | Arecaceae | Bu |
| Pilgerina | Robert Knud Friedrich Pilger (1876–1953) | Santalaceae | Bu |
| Pilgerodendron | Robert Knud Friedrich Pilger (1876–1953) | Cupressaceae | Bu |
| Pillansia | Neville Stuart Pillans (1884–1964), South African botanist at the Bolus Herbarium in Cape Town | Iridaceae | Bu |
| Pineda | Antonio Pineda (1753–1792) | Salicaceae | Bu |
| Pinellia | Gian Vincenzo Pinelli (1535–1601) | Araceae | St |
| Pinillosia | Claudio Martinez de Pinillos y Ceballos (1782–1853), Cuban military officer, governor and economist who supported science, literature and the mechanization of industry | Asteraceae | Bu |
| Pinochia | Marcel Pichon (1921–1954) | Apocynaceae | Bu |
| Pintoa | Francisco Antonio Pinto (1785–1858), president of Chile | Zygophyllaceae | Bu |
| Pinzona | Vicente Yáñez Pinzón (c. 1462 – after 1514), naval officer and explorer | Dilleniaceae | Bu |
| Pippenalia | Richard Wayne Pippen (b. 1935), American botanist at the University of Michigan | Asteraceae | Bu |
| Piqueria | Andrés Piquer (1711–1772) | Asteraceae | St |
| Piqueriella | Andrés Piquer (1711–1772) | Asteraceae | Bu |
| Piresia | João Murça Pires (1917–1994) | Poaceae | Bu |
| Piresiella | João Murça Pires (1917–1994) | Poaceae | Bu |
| Pisonia | Willem Piso (1611–1678) | Nyctaginaceae | Ba |
| Pisoniella | Willem Piso (1611–1678) | Nyctaginaceae | Qu |
| Pistorinia | Santiago Pistorini (d. 1776), Italian-Spanish doctor, personal physician to Charles III | Crassulaceae | Bu |
| Pitardella | Charles-Joseph Marie Pitard (1873–1927) | Rubiaceae | Bu |
| Pitcairnia | William Pitcairn (1711–1791) | Bromeliaceae | St |
| Pitraea | Adolf Samoilovich Pitra (1830–1889), Russian professor of botany in Kharkiv | Verbenaceae | Bu |
| Pittoniotis | Joseph Pitton de Tournefort (1656–1708) | Rubiaceae | Bu |
| Planchonella | Jules Émile Planchon (1823–1888) | Sapotaceae | Bu |
| Planchonia | Jules Émile Planchon (1823–1888) | Lecythidaceae | Bu |
| Planera | Johann Jakob Planer (1743–1789), German professor and botanist | Ulmaceae | St |
| Platonia | Plato (427 BC – 347 BC), philosopher and writer | Clusiaceae | Bu |
| Platyschkuhria | Christian Schkuhr (1741–1811) | Asteraceae | Bu |
| Plazia | Juan Plaza (16th century), Spanish doctor and botanist; professor of medicine in Valencia | Asteraceae | Bu |
| Plenckia | Joseph Jakob Plenck (1735–1807), doctor | Celastraceae | Bu |
| Plinia | Pliny the Elder (c. 23 – 79) | Myrtaceae | Bu |
| Plowmania | Timothy Plowman (1944–1989) | Solanaceae | Bu |
| Plowmanianthus | Timothy Plowman (1944–1989) | Commelinaceae | Bu |
| Pluchea | Noël-Antoine Pluche (1688–1761) | Asteraceae | Bu |
| Plukenetia | Leonard Plukenet (1642–1706) | Euphorbiaceae | Bu |
| Plumeria | Charles Plumier (1646–1704) | Apocynaceae | St |
| Plutarchia | Plutarch (c. 45 – c. 125), philosopher and writer | Ericaceae | Bu |
| Poeppigia | Eduard Friedrich Poeppig (1798–1868) | Fabaceae | Bu |
| Poggea | Paul Pogge (1838–1884) | Achariaceae | Bu |
| Pohlidium | Richard Walter Pohl (1916–1993), American botanist at the University of Iowa; specialist in grasses | Poaceae | Bu |
| Pohliella | Josef Pohl (1864–1939), German botanical illustrator | Podostemaceae | Bt |
| Poilanedora | Eugène Poilane (1888–1964), French plant collector at the botanical institute in present-day Ho Chi Minh City, Vietnam; also worked in the forest service | Capparaceae | Bu |
| Poilannammia | Eugène Poilane (1888–1964), French plant collector at the botanical institute in present-day Ho Chi Minh City, Vietnam; also worked in the forest service | Melastomataceae | Bu |
| Poiretia | Jean Louis Marie Poiret (1755–1834) | Fabaceae | Bu |
| Poissonia | Jules Poisson (1833–1919), French botanist at the National Museum of Natural History; collected plants in New Caledonia | Fabaceae | Bu |
| Poitea | Pierre Antoine Poiteau (1766–1854) | Fabaceae | Bu |
| Pojarkovia | Antonina Pojarkova (1897–1980) | Asteraceae | Bu |
| Polaskia | Charles Polaski (1898–1986), American cactus and Camellia collector from Oklahoma City | Cactaceae | Bu |
| Polemannia | Peter Heinrich Polemann (1779 – 1839), German chemist and apothecary who supported plant collectors in Schleswig-Holstein; went to Cape Town, South Africa | Apiaceae | Bu |
| Polemanniopsis | Peter Heinrich Polemann (1779 – 1839), German chemist and apothecary who supported plant collectors in Schleswig-Holstein; went to Cape Town, South Africa | Apiaceae | Bu |
| Polevansia | Illtyd Buller Pole-Evans (1879–1968) | Poaceae | Bu |
| Polhillia | Roger Marcus Polhill (b. 1937), English botanist at Kew Gardens with a focus on Fabaceae; collected in Africa | Fabaceae | Bu |
| Polhillides | Roger Marcus Polhill (b. 1937), English botanist at Kew Gardens with a focus on Fabaceae; collected in Africa | Fabaceae | Bt |
| Poljakanthema | Petr Petrovich Poljakov (1902–1974), Russian botanist; specialist in Asteraceae and sub-Siberian plants | Asteraceae | Bu |
| Poljakovia | Petr Petrovich Poljakov (1902–1974), Russian botanist; specialist in Asteraceae and sub-Siberian plants | Asteraceae | Bu |
| Pollia | Jan van der Poll (18th century), Dutch consul who supported Carl Peter Thunberg | Commelinaceae | Bu |
| Pollichia | Johan Adam Pollich (1740–1780) | Caryophyllaceae | Bu |
| Polyclita | Polykleitos (c. 480 BC – end of the 5th century BC), Greek sculptor of bronzes (copies of which probably persist as Roman marble statues) | Ericaceae | Bu |
| Pomaria | Jaime Honorato Pomar (c. 1550 – 1606), Spanish doctor and botanist, professor of medicine in Valencia; also a royal personal physician | Fabaceae | Bu |
| Pombalia | Sebastião José de Carvalho e Melo, 1st Marquis of Pombal (1699–1782) | Violaceae | Bu |
| Pometia | Pierre Pomet (1658–1699) | Sapindaceae | Bu |
| Pommereschea | Robert von Pommer Esche (1833–1898), Prussian official, director of a horticultural society | Zingiberaceae | Bu |
| Pommereulla | (Madame) du Gage, born Elisabeth Julienne Pommereull (1733–1782); French botanist; specialist in grasses | Poaceae | Bu |
| Pontederia | Giulio Pontedera (1688–1757) | Pontederiaceae | Ch |
| Ponthieva | Henry de Ponthieu (1731–1808) | Orchidaceae | Qu |
| Poortmannia | Hugo Anne Cornelis Poortman (1858–1953), Dutch garden architect; collected plants in Colombia and Ecuador; created various manor and castle gardens | Solanaceae | Bu |
| Popowia | Johannes Siegmund Valentin Popowitsch (1705–1774), Austrian linguist and naturalist, professor of German language and linguistics at the university in Vienna; built up a large herbarium | Annonaceae | Bu |
| Porcelia | Antonio Porcel Román (1755–1832), Spanish botanical patron who helped Hipólito Ruiz López and José Antonio Pavón Jiménez | Annonaceae | Bu |
| Porlieria | Antonio Porlier, Marques de Bajamar (1722–1813), Spanish lawyer and judge in Madrid and Lima, Peru | Zygophyllaceae | Bu |
| Portea | Marius Porte (d. 1866), French explorer and naturalist | Bromeliaceae | St |
| Portenschlagiella | Franz Edler von Portenschlag-Ledermayr (1772–1822), Austrian lawyer and botanist; collected in the Alps and the Dalmatian islands | Apiaceae | Bu |
| Porterandia | George Isaac Porter (1800–1848), British gardener with the East India Company in present-day Kolkata; plant collector and teacher in Penang in present-day Malaysia | Rubiaceae | Bu |
| Porterella | Thomas Conrad Porter (1822–1901) | Campanulaceae | Bu |
| Portlandia | Margaret Bentinck, Duchess of Portland (1715–1785) | Rubiaceae | St |
| Poskea | Friedrich Poske (1852–1925), German teacher and natural scientist in Berlin | Plantaginaceae | Bu |
| Postiella | George Edward Post (1838–1909) | Apiaceae | Bu |
| Potaninia | Grigory Potanin (1835–1920) | Rosaceae | Bu |
| Pottingeria | Eldred Charles Pottinger (1868–1929), military doctor in the army in India; assisted the author of this genus with the flora in Kachin in Burma (present-day Myanmar) | Celastraceae | Bu |
| Pottsia | John Potts (d. 1822), English gardener and plant collector for the Royal Horticultural Society | Apocynaceae | Bu |
| Pouchetia | Félix Archimède Pouchet (1800–1872) | Rubiaceae | Bu |
| Poulsenia | Viggo Albert Poulsen (1855–1919), Danish professor of botany at the pharmacy school in Copenhagen; also worked in present-day Bogor in Indonesia | Moraceae | Bu |
| Poupartia | François Poupart (d. 1708) | Anacardiaceae | Bu |
| Poupartiopsis | François Poupart (d. 1708) | Anacardiaceae | Bu |
| Pourthiaea | J. A. Pourthié (1830–1866), French clergyman; missionary in Korea | Rosaceae | Bu |
| Pouzolzia | Pierre Marie Casimir de Pouzolz (1785–1858), French botanist and plant collector from Nîmes | Urticaceae | Bu |
| Pozoa | José Pozo (fl. 1800), Spanish botanist at a botanical garden in Madrid | Apiaceae | Bu |
| Pradosia | Camilo Maria Ferreira Armond, Conde de Prados (1815–1882), Brazilian doctor and politician, director of the observatory in Rio de Janeiro | Sapotaceae | Bu |
| Prainea | David Prain (1857–1944) | Moraceae | Bu |
| Pranceacanthus | Ghillean Prance (b. 1937) | Acanthaceae | Bu |
| Pratia | Charles Louis Prat-Bernon (1795–1817), French naval officer | Campanulaceae | St |
| Prescottia | John D. Prescott (1760–1837), English doctor and botanist in Saint Petersburg in Russia | Orchidaceae | Bu |
| Presliophytum | Carl Borivoj Presl (1794–1852) | Loasaceae | Bu |
| Prestelia | Michael August Friedrich Prestel (1809–1880), German mathematician, meteorologist and cartographer; professor of mathematics and natural science at a school in Emden, and director of the naturalist society there | Asteraceae | Bu |
| Prestoea | Henry Prestoe (1842–1923), British naturalist, gardener and botanist; botanical garden director in Trinidad | Arecaceae | Bu |
| Prestonia | Charles Preston (1660–1711), Scottish doctor and botanist | Apocynaceae | Bu |
| Preussiella | Paul Rudolf Preuss (1861–1926), German botanist and researcher; founded and directed a botanical garden in Kamerun (now Cameroon) | Melastomataceae | Bu |
| Preussiodora | Paul Rudolf Preuss (1861–1926), German botanist and researcher; founded and directed a botanical garden in Kamerun (now Cameroon) | Rubiaceae | Bu |
| Pringlea | John Pringle, 1st Baronet (1707–1782) | Brassicaceae | Bu |
| Prinsepia | James Prinsep (1799–1840) | Rosaceae | Co |
| Printzia | Jacob Printz (1740–1779), Swedish botanist, student of Carl Linnaeus | Asteraceae | Bu |
| Prioria | Alexander Prior (1809–1902), English doctor and botanist; collected in South Africa and North America | Fabaceae | Bu |
| Pritchardia | William Thomas Pritchard (1829–1907), adventurer | Arecaceae | St |
| Prockia | Christian Leberecht von Prøck (1718–1780), baron | Salicaceae | Bu |
| Prockiopsis | Christian Leberecht von Prøck (1718–1780), baron | Achariaceae | Bu |
| Prolongoa | Pablo Prolongo y García (1806–1885), Spanish apothecary and local plant collector; founded a pharmacology school in Málaga | Asteraceae | Bu |
| Promenaea | Promenaea, Greek priestess of Dodona | Orchidaceae | St |
| Proustia | Joseph Proust (1754–1826) | Asteraceae | Bu |
| Przewalskia | Nikolay Przhevalsky (1839–1888) | Solanaceae | Bu |
| Puccinellia | Benedetto Luigi Puccinelli (1808–1850), Italian doctor and botanist; taught chemistry, physics, pharmacology and agricultural science in Lucca; botanical garden director | Poaceae | Bu |
| Puelia | Timothée Puel (1813–1890) | Poaceae | Bu |
| Pueraria | Marc Nicolas Puerari (1766–1845), Swiss botanist | Fabaceae | St |
| Puhuaea | Pu Hwa Huang (b.1932), Chinese botanist | Fabaceae | Bt |
| Pullea | August Adriaan Pulle (1878–1955) | Cunoniaceae | Bu |
| Pullenia | Royal 'Roy' Pullen (1925 - 2009), Australian plant collector | Fabaceae | Bt |
| Pultenaea | Richard Pulteney (1730–1801) | Fabaceae | St |
| Purdiaea | William Purdie (c. 1817 – 1857), Scottish gardener at botanical gardens in Edinburgh and Trinidad; collected in Jamaica, Colombia and Venezuela | Clethraceae | Bu |
| Purdieanthus | William Purdie (c. 1817 – 1857), Scottish gardener at botanical gardens in Edinburgh and Trinidad; collected in Jamaica, Colombia and Venezuela | Gentianaceae | Bu |
| Purshia | Frederick Traugott Pursh (1774–1820) | Rosaceae | Co |
| Puschkinia | Apollo Mussin-Pushkin (1760–1805) | Asparagaceae | Co |
| Putterlickia | Aloys Putterlick (1810–1845), Austrian doctor and botanist (bryologist); natural history museum curator in Vienna | Celastraceae | Bu |