# List of the largest genera of flowering plants

There are over 56 genera of flowering plants estimated to contain at least 500 described species. The largest of these is currently the legume genus Astragalus (milk-vetches), with over 3,000 species.
The sizes of plant genera vary widely from those containing a single species to genera containing thousands of species, and this disparity became clear early in the history of plant classification. The largest genus in Carl Linnaeus' seminal Species Plantarum was Euphorbia, with 56 species; Linnaeus believed that no genus should contain more than 100 species.
Part of the disparity in genus sizes is attributable to historical factors. According to a hypothesis published by Max Walters in 1961, the size of plant genera is related to the age, not of the taxon itself, but of the concept of the taxon in the minds of taxonomists. Plants which grew in Europe, where most of the early taxonomy was based, were therefore divided into relatively small genera, while those from the tropics were grouped into much larger and more heterogeneous genera. Likewise, plants which shared common medicinal properties, such as the many species of Euphorbia, were united into a single genus, while plants of diverse uses, such as the grasses, were split into many genera. Where there were many classical names for groups of plants, such as in Apiaceae / Umbelliferae or Brassicaceae / Cruciferae, small genera were defined, whereas groups not subdivided by classical authors remained as larger genera, such as Carex. A number of biological factors also influence the number of species. For instance, the occurrence of apomixis allows the recognition of large numbers of agamospecies, and such taxa have helped to bolster genera such as Ranunculus and Potentilla.
The introduction of infrageneric taxa (such as the subgenus, section and series) in the 19th century by botanists including Augustin Pyrame de Candolle allowed the retention of large genera that would otherwise have become unwieldy. E. J. H. Corner believed that studying large genera might enable greater insights into evolutionary biology, and he concentrated his efforts on large tropical genera such as Ficus.

## Largest genera

According to a 2004 analysis by the botanical taxonomist David G. Frodin, a total of 57 genera of flowering plants contain at least 500 species. It is clear that there are other genera with over 500 species, as the work of taxonomists continues. Currently the number of species included in many genera is very different (e.g. see Psychotria), so their ranking is subject to changes. The actual numbers of species are imprecisely known also because of different approaches of taxonomists, and many of the genera have not been the subject of recent monographs. For instance, estimates of the number of species in the orchid genus Pleurothallis range from 1,120 to 2,500. Genera from some other groups of vascular plants (like pteridophytes), which have similarly large numbers of species, include Selaginella, Asplenium and Cyathea.
Genera of flowering plants with at least 500 species in 2025 :
| Rank | Genus | Species | Family | Species list |
| 1 | Astragalus | 3,092 | Fabaceae | List of Astragalus species |
| 2 | Piper | 2,424 | Piperaceae | List of Piper species |
| 3 | Bulbophyllum | 2,181 | Orchidaceae | List of Bulbophyllum species |
| 4 | Begonia | 2,088 | Begoniaceae | List of Begonia species |
| 5 | Carex | 2,080 | Cyperaceae | List of Carex species |
| 6 | Euphorbia | 2,055 | Euphorbiaceae | List of Euphorbia species |
| 7 | Miconia | 1,902 | Melastomataceae | List of Miconia species |
| 8 | Epidendrum | 1,878 | Orchidaceae | List of Epidendrum species |
| 9 | Ranunculus | 1,750 | Ranunculaceae | List of Ranunculus species |
| 10 | Psychotria | 1,643 | Rubiaceae | List of Psychotria species |
| 11 | Dendrobium | 1,593 | Orchidaceae | List of Dendrobium species |
| 12 | Senecio | 1,475 | Asteraceae | List of Senecio species |
| 13 | Peperomia | 1,422 | Piperaceae | List of Peperomia species |
| 14 | Anthurium | 1,327 | Araceae | List of Anthurium species |
| 15 | Syzygium | 1,236 | Myrtaceae | List of Syzygium species |
| 16 | Solanum | 1,235 | Solanaceae | List of Solanum species |
| 17 | Eugenia | 1,227 | Myrtaceae | List of Eugenia species |
| 18 | Lepanthes | 1,203 | Orchidaceae | List of Lepanthes species |
| 19 | Croton | 1,124 | Euphorbiaceae | List of Croton species |
| 20 | Impatiens | 1,121 | Balsaminaceae | List of Impatiens species |
| 21 | Rhododendron | 1,091 | Ericaceae | List of Rhododendron species |
| 22 | Allium | 1,089 | Amaryllidaceae | List of Allium species |
| 23 | Acacia | 1,085 | Fabaceae | List of Acacia species |
| 24 | Phyllanthus | 1,044 | Phyllanthaceae | List of Phyllanthus species |
| 25 | Salvia | 1,024 | Lamiaceae | List of Salvia species |
| 26 | Cyperus | 949 | Cyperaceae | List of Cyperus species |
| 27 | Justicia | 913 | Acanthaceae | List of Justicia species |
| 28 | Silene | 907 | Caryophyllaceae | List of Silene species |
| 29 | Habenaria | 896 | Orchidaceae | List of Habenaria species |
| 30 | Ficus | 880 | Moraceae | List of Ficus species |
| 31 | Erica | 842 | Ericaceae | List of Erica species |
| 32 | Diospyros | 778 | Ebenaceae | List of Diospyros species |
| 33 | Centaurea | 770 | Asteraceae | List of Centaurea species |
| 34 | Indigofera | 761 | Fabaceae | |
| 35 | Ardisia | 738 | Primulaceae | List of Ardisia species |
| 36 | Crotalaria | 717 | Fabaceae | List of Crotalaria species |
| 37 | Cyrtandra | 683 | Gesneriaceae | List of Cyrtandra species |
| 38 | Eucalyptus | 715 | Myrtaceae | List of Eucalyptus species |
| 39 | Cousinia | 672 | Asteraceae | List of Cousinia species |
| 40 | Galium | 645 | Rubiaceae | List of Galium species |
| 41 | Ipomoea | 637 | Convolvulaceae | List of Ipomoea species |
| 42 | Dioscorea | 634 | Dioscoreaceae | |
| 43 | Berberis | 614 | Berberidaceae | List of Berberis species |
| 44 | Pleurothallis | 582 | Orchidaceae | List of Pleurothallis species |
| 45 | Oxalis | 568 | Oxalidaceae | List of Oxalis species |
| 46 | Helichrysum | 562 | Asteraceae | List of Helichrysum species |
| 47 | Pandanus | 561 | Pandanaceae | List of Pandanus species |
| 48 | Ixora | 556 | Rubiaceae | List of Ixora species |
| 49 | Potentilla | 510 | Rosaceae | List of Potentilla species |
NB - all species counts have been updated to the 3rd of March 2025 as accepted by Plants of the World Online (POTWO) and genera with lower than 500 species as of then have been removed, but no genus has been added to this list differing from the 2004 list so there may be some missing relevant genera.