Penstemon

Penstemon , the beardtongues, is a large genus of roughly 280 species of flowering plants native mostly to the Nearctic, but with a few species also found in the North American portion of the Neotropics. It is the largest genus of flowering plants endemic to North America. As well as being the scientific name, penstemon is also widely used as a common name for all Penstemon species alongside beardtongues.
Formerly placed in the family Scrophulariaceae by the Cronquist system, new genetic research has placed it in the vastly expanded family Plantaginaceae. The total number of species is uncertain due to on going research into if some of the named species are actually subspecies or misidentifications of already identified species.
Description
They have opposite leaves, partly tube-shaped, and two-lipped flowers and seed capsules. The most distinctive feature of the genus is the prominent staminode, an infertile stamen. The staminode takes a variety of forms in the different species; while it is typically a long straight filament extending to the mouth of the corolla, some are longer and extremely hairy, giving the general appearance of an open mouth with a fuzzy tongue protruding and inspiring the common name of "beardtongue".
Most penstemons form a durable woody stem (a caudex) and have persistent basal leaves, but some are fully deciduous perennials, the remainder being shrubs or subshrubs. Heights can range from 10 cm to as much as 3 meters. Along with their variable growth forms the penstemons have highly variable leaves, often with different leaf shapes on different parts of the same plant. Some species have highly reduced needle like leaves and others broad and rounded leaves, with their texture also running the range of hairy to smooth/glaborous. In the view of penstemon expert Robert Nold the defining evolutionary characteristic of the genus is adaptation to drought, as demonstrated by their numbers and diversity in the interior west of North America.
The one Asiatic species previously treated in Penstemon is now placed in a separate genus Pennellianthus. This leaves Penstemon a mostly Nearctic genus, with a few neotropical species. Although widespread across North America, and found in habitats ranging from open desert to moist forests, and up to the alpine zone, they are not typically common within their range.
History
John Mitchell published the first scientific description in 1748; although he only named it as Penstemon, researchers David Way, Peter James, and Robert Nold identify it as P. laevigatus. Linnaeus then included it in his 1753 publication, as Chelone pentstemon, altering the spelling to better correspond to the notion that the name referred to the unusual fifth stamen (Greek "penta-", five). The botanist Casimir Schmidel published a description of the species in 1763, and for this reason he is given priority in botanical publication. Mitchell's work was reprinted in 1769, continuing with his original spelling, and this was ultimately accepted as the official form, although Pentstemon continued in use into the 20th century.
Although several more species were found in the early 18th century, they continued to be classified in Chelone until 1828 in some publications. The period of 1810 to 1850 increased the number of known species from 4 to 63, as expeditions traveled through Mexico and the western United States, followed by another 100 up to 1900, although not all these species remained classified as Penstemon.
The American members of the genus were extensively revised by David D. Keck between 1932 and 1957 and Richard Straw did similar work on the Mexican species slightly later. In 1960 the important book Penstemon Taxonomy was published by American Penstemon Society president Ralph Bennett with the advice of Keck. This book was updated and republished with the Robin Lodewick in 1980 and continued to be an important source of information about the genus through the year 2000.
Fieldwork in the remote parts of the Great Basin during the 20th century brought the total number of species known to over 270, though some of this total may be errors or now extinct species.
Penstemon has been subdivided into six subgenera by using anther dehiscence patterns. Subgenera Cryptostemon and Dissecti each contain one species. As traditionally defined subgenus Penstemon contains about 128 species, subgenus Habroanthus contains about 50, subgenus Saccanthera has about 28 species, and subgenus Dasanthera contains nine. Genetic analysis by Andrea D Wolfe et al. indicates that while some of the previously identified subgenera are natural groupings, many are hopelessly confused.
Horticulture
Although penstemons are among the most attractive native flowers of North America, Europe has traditionally been far more active in their hybridization with hundreds of hybrids developed since the early 19th century. The first offer of seeds for sale as by John Fraser in 1813. The earliest development is somewhat shrouded in mystery; for instance Flanagan & Nutting's 1835 catalog mentions a 'Penstemon Hybridum' but does not describe it.
By 1860, a half-dozen French growers are known to have developed hybrids, most notably Victor Lemoine, while in 1857 the German Wilhelm Pfitzer listed 24 varieties. In 1861 the British Royal Horticultural Society held trials in which 78 varieties were entered. The Scottish firm of John Forbes first offered penstemons in 1870, eventually becoming the biggest grower in the world; in 1884 their catalog listed 180 varieties. By 1900 Forbes had offered 550 varieties, while Lemoine had developed nearly 470 by the time of his death in 1911. Few of these have survived to the present day.
A number of different species have been used in the hybridization process, notably P. cobaea and P. hartwegii.
The American Penstemon Society was formed in 1946 to promote both horticultural and botanical interest, and is now the International Cultivar Registration Authority for the genus.
In North America, penstemons are often used in xeriscape landscaping, as many are native to desert or alpine regions and thus quite hardy. One of the largest collections of penstemons in North America is found at The Arboretum at Flagstaff, Arizona, which hosts a Penstemon Festival each summer.
Cultivars
The following species and cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-
'Andenken an Friedrich Hahn' (deep red)
'Beech Park' (pink/white)
'Connie's Pink' (rose pink)
'Evelyn' (rose pink)
'George Home' (red/white)
'Hewell Pink Bedder' (pink/white)
'Hidcote Pink'
'Margery Fish' (purple/blue)
'Maurice Gibbs' (purple-red/white)
'Osprey' (pink/white)
P. hartwegii (scarlet)
P. isophyllus (pale pink)
P. pinifolius 'Wisley Flame' (orange-red)
P. rupicola (pink)
'Port Wine' (deep red/white)
'Raven' (purple/white)
'Rich Ruby'
'Roy Davidson' (pink/white)
'Rubicundus' (red/white)
'Schoenholzeri' (red)
'Sour Grapes' (purple/blue)
'Stapleford Gem' (purple/blue)
Others include 'Dark Towers', developed by Dale Lindgren at the University of Nebraska.
Species
These 269 species are valid according to both World Flora Online (WFO) and Plants of the World Online (POWO) as of 2023.
Penstemon abietinus Pennell – Firleaf beardtongue
Penstemon absarokensis Evert – Absaroka Range beardtongue
Penstemon acaulis L.O.Williams – Stemless beardtongue
Penstemon acuminatus Douglas ex Lindl. – Sharpleaf penstemon
Penstemon alamosensis Pennell & G.T.Nisbet – Los Alamos beardtongue
Penstemon albertinus Greene – Alberta beardtongue
Penstemon albidus Nutt. – White penstemon
Penstemon albomarginatus M.E.Jones – White margin penstemon, whitemargin beardtongue, whitemargin penstemon
Penstemon ambiguus Torr. – bush penstemon, gilia beardtongue, gilia penstemon
Penstemon ammophilus N.H.Holmgren & L.M.Schultz – sandloving penstemon
Penstemon amphorellae Crosswh.
Penstemon anguineus Eastw. – Siskiyou beardtongue
Penstemon angustifolius Nutt. ex Pursh – broad-beard beardtongue, broadbeard beardtongue, narrowleaf penstemon
Penstemon arenarius Greene – Nevada sanddune beardtongue, sanddune penstemon
Penstemon arenicola A.Nelson – sand penstemon
Penstemon aridus Rydb. – stiffleaf penstemon
Penstemon arkansanus Pennell – Arkansas beardtongue
Penstemon atropurpureus (Sweet) G.Don
Penstemon attenuatus Douglas – sulphur penstemon
Penstemon atwoodii S.L.Welsh – Kaiparowits beardtongue
Penstemon auriberbis Pennell – Colorado beardtongue
Penstemon australis Small – Eustis Lake beardtongue
Penstemon azureus Benth. – azure penstemon
Penstemon baccharifolius Hook. – baccharisleaf beardtongue
Penstemon barbatus (Cav.) Roth – Golden-beard Penstemon or Beardlip penstemon
Penstemon barnebyi N.H.Holmgren – Barneby's penstemon, White River Valley beardtongue
Penstemon barrettiae A.Gray – Barrett's beardtongue
Penstemon bicolor (Brandegee) Clokey & D.D.Keck – pinto beardtongue, pinto penstemon
Penstemon bleaklyi O'Kane & K.D.Heil
Penstemon bolanus Straw
Penstemon bracteatus D.D.Keck – Red Canyon beardtongue
Penstemon bradburyi Pursh
Penstemon breviculus (D.D.Keck) G.T.Nisbet & R.C.Jacks. – shortstem beardtongue, shortstem penstemon
Penstemon brevisepalus Pennell – short-sepaled beardtongue
Penstemon buckleyi Pennell – buckley penstemon, Buckley's beardtongue
Penstemon caesius A.Gray – San Bernardino beardtongue
Penstemon caespitosus Nutt. ex A.Gray – mat penstemon
Penstemon calcareus Brandegee – limestone beardtongue
Penstemon californicus (Munz & I.M.Johnst.) D.D.Keck – California penstemon
Penstemon calycosus Small – longsepal beardtongue
Penstemon campanulatus (Cav.) Willd. – bellflower beardtongue
Penstemon canescens Britton – eastern gray beardtongue
Penstemon cardinalis Wooton & Standl. – cardinal beardtongue
Penstemon cardwellii Howell – Cardwell's beardtongue
Penstemon carnosus Pennell – fleshy beardtongue
Penstemon caryi Pennell – Cary's beardtongue
Penstemon cedrosensis Krautter
Penstemon centranthifolius (Benth.) Benth. – scarlet bugler
Penstemon cinicola D.D.Keck – ash penstemon
Penstemon clevelandii A.Gray – Cleveland's beardtongue
Penstemon clutei A.Nelson – Sunset Crater beardtongue, Sunset Crater penstemon
Penstemon cobaea Nutt. – cobaea beardtongue, Cobaea penstemon
Penstemon comarrhenus A.Gray – dusty beardtongue, dusty penstemon
Penstemon concinnus D.D.Keck – Tunnel Springs beardtongue, Tunnel Springs penstemon
Penstemon confertus Douglas – yellow penstemon
Penstemon confusus M.E.Jones – Owens Valley beardtongue, Owens Valley penstemon
Penstemon crandallii A.Nelson – Crandall's beardtongue
Penstemon cusickii A.Gray – Cusick's beardtongue
Penstemon cyananthus Hook. – Wasatch beardtongue
Penstemon cyaneus Pennell – blue penstemon
Penstemon cyanocaulis Payson – bluestem beardtongue
Penstemon cyathophorus Rydb. – Northpark penstemon, sagebrush beardtongue
Penstemon dasyphyllus A.Gray – Cochise beardtongue, purple penstemon
Penstemon davidsonii Greene – Davidson's penstemon, timberline penstemon
Penstemon deamii Pennell – Deam's beardtongue
Penstemon deaveri Crosswh. – Mt. Graham beardtongue
Penstemon debilis O'Kane & J.L.Anderson – Parachute beardtongue
Penstemon degeneri Crosswh. – Degener's beardtongue
Penstemon deustus Douglas ex Lindl. – scabland penstemon
Penstemon digitalis Nutt. ex Sims – talus slope penstemon, foxglove beardtongue
Penstemon diphyllus Rydb. – twoleaf beardtongue
Penstemon discolor D.D.Keck – Catalina beardtongue
Penstemon dissectus Elliott – dissected beardtongue
Penstemon distans N.H.Holmgren – Mt. Tumbull beardtongue
Penstemon dolius M.E.Jones – Jones's penstemon, Jones' beardtongue
Penstemon duchesnensis (N.H.Holmgren) Neese
Penstemon eatonii A.Gray – Eaton penstemon, Eaton's penstemon, firecracker penstemon
Penstemon elegantulus Pennell – rockvine penstemon
Penstemon ellipticus J.M.Coult. & Fisher – rocky ledge penstemon
Penstemon erianthera Fraser ex Nutt. – fuzzytongue penstemon
Penstemon euglaucus English – glaucous beardtongue
Penstemon eximius D.D.Keck – unusual beardtongue
Penstemon fasciculatus A.Gray
Penstemon fendleri Torr. & A.Gray – fendler penstemon, Fendler's beardtongue, Fendler's penstemon
Penstemon filiformis (D.D.Keck) D.D.Keck – Keck threadleaf beardtongue
Penstemon filisepalis Straw
Penstemon flavescens Pennell – high mountain penstemon
Penstemon floribundus Danley – Cordillia's beardtongue, Cordillia's penstemon
Penstemon floridus Brandegee – Panamint beardtongue, Panamint penstemon
Penstemon flowersii Neese & S.L.Welsh – Flowers' beardtongue
Penstemon franklinii S.L.Welsh – Franklin's penstemon
Penstemon fremontii Torr. & A.Gray – Fremont penstemon, Fremont's beardtongue
Penstemon fruticiformis Coville – Death Valley beardtongue, Death Valley penstemon
Penstemon fruticosus (Pursh) Greene – Greene bush penstemon
Penstemon gairdneri Hook. – Gairdner's beardtongue
Penstemon galloensis G.L.Nesom
Penstemon gentianoides (Kunth) Poir.
Penstemon gentryi Standl.
Penstemon gibbensii Dorn – Gibbens' beardtongue
Penstemon glaber Pursh – sawsepal penstemon, western smooth beardtongue
Penstemon glandulosus Douglas ex Lindl. – stickystem penstemon
Penstemon glaucinus Pennell – blueleaf beardtongue
Penstemon globosus (Piper) Pennell & D.D.Keck – globe penstemon
Penstemon goodrichii N.H.Holmgren – Lapoint beardtongue
Penstemon gormanii Greene – Gorman's beardtongue
Penstemon gracilentus A.Gray – slender penstemon
Penstemon gracilis Nutt. – lilac penstemon, slender penstemon
Penstemon grahamii D.D.Keck – Uinta Basin beardtongue
Penstemon griffinii A.Nelson – Griffin's beardtongue
Penstemon grinnellii Eastw. – Grinnell's beardtongue
Penstemon guadalupensis A.Heller – Guadalupe beardtongue
Penstemon hallii A.Gray – Hall's beardtongue
Penstemon harbourii A.Gray – Harbour's beardtongue
Penstemon harringtonii Penland – Harrington's beardtongue
Penstemon hartwegii Benth. – Hartweg's beardtongue
Penstemon havardii A.Gray – Big Bend beardtongue
Penstemon haydenii S.Watson ex J.M.Coult. – blowout beardtongue, blowout penstemon
Penstemon henricksonii Straw
Penstemon heterodoxus A.Gray – Sierra beardtongue, Sierra penstemon
Penstemon heterophyllus Lindl. – bunchleaf penstemon
Penstemon hidalgensis Straw
Penstemon hirsutus (L.) Willd. – hairy beardtongue
Penstemon humilis Nutt. ex A.Gray – low beardtongue, low penstemon
Penstemon imberbis (Kunth) Trautv.
Penstemon immanifestus N.H.Holmgren – Steptoe Valley beardtongue, Steptoe Valley penstemon
Penstemon incertus Brandegee – Mojave beardtongue
Penstemon inflatus Crosswh. – inflated beardtongue
Penstemon isophyllus B.L.Rob.
Penstemon jamesii Benth. – James penstemon, James' beardtongue
Penstemon janishiae N.H.Holmgren – Antelope Valley beardtongue, Janish's penstemon
Penstemon kingii S.Watson – King's beardtongue, King's penstemon
Penstemon kralii D.Estes
Penstemon labrosus (A.Gray) Mast. ex Hook.f. – San Gabriel beardtongue
Penstemon laetus A.Gray – mountain blue penstemon
Penstemon laevigatus Aiton – eastern smooth beardtongue
Penstemon laevis Pennell – southwestern beardtongue, southwestern penstemon
Penstemon lanceolatus Benth.
Penstemon laricifolius Hook. & Arn. – larchleaf beardtongue
Penstemon laxiflorus Pennell – nodding beardtongue
Penstemon laxus A.Nelson – tufted penstemon
Penstemon leiophyllus Pennell – smoothleaf beardtongue, smoothleaf penstemon
Penstemon lemhiensis (D.D.Keck) D.D.Keck & Cronquist – Lemhi penstemon
Penstemon lentus Pennell – handsome beardtongue, handsome penstemon
Penstemon leonardii Rydb. – Leonard's beardtongue, Leonard's penstemon
Penstemon leonensis Straw
Penstemon linarioides A.Gray – creeping penstemon, toadflax penstemon
Penstemon longiflorus (Pennell) S.L.Clark – longflower penstemon
Penstemon luteus G.L.Nesom
Penstemon lyallii (A.Gray) A.Gray – Lyall's beardtongue
Penstemon marcusii (D.D.Keck) N.H.Holmgren – Marcus' beardtongue
Penstemon mensarum Pennell – tiger beardtongue
Penstemon metcalfei Wooton & Standl. – Metcalfe's beardtongue
Penstemon miniatus Lindl.
Penstemon miser A.Gray – Malheur penstemon
Penstemon moffatii Eastw. – Moffatt's beardtongue
Penstemon mohinoranus Straw
Penstemon monoensis A.Heller – Mono penstemon
Penstemon montanus Greene – cordroot beardtongue
Penstemon moriahensis N.H.Holmgren – Mount Moriah penstemon, Mt. Moriah beardtongue
Penstemon mucronatus N.H.Holmgren
Penstemon multiflorus (Benth.) Chapm. ex Small – manyflower beardtongue
Penstemon murrayanus Hook. – scarlet beardtongue
Penstemon nanus D.D.Keck – dwarf beardtongue
Penstemon navajoa N.H.Holmgren – Navajo Mountain beardtongue
Penstemon neomexicanus Wooton & Standl. – New Mexico beardtongue
Penstemon neotericus D.D.Keck – Plumas County beardtongue
Penstemon newberryi A.Gray – mountain pride, pride-of-the-mountains
Penstemon nitidus Douglas ex Benth. – waxleaf penstemon
Penstemon nudiflorus A.Gray – Flagstaff beardtongue
Penstemon occiduus Straw
Penstemon oklahomensis Pennell – Oklahoma beardtongue, Oklahoma penstemon
Penstemon oliganthus Wooton & Standl. – Apache beardtongue
Penstemon ophianthus Pennell – Arizona beardtongue, coiled anther penstemon
Penstemon osterhoutii Pennell – Osterhout's beardtongue
Penstemon ovatus Douglas – eggleaf beardtongue
Penstemon pachyphyllus A.Gray ex Rydb. – thickleaf beardtongue, thickleaf penstemon
Penstemon pahutensis N.H.Holmgren – Pahute penstemon, Paiute beardtongue
Penstemon pallidus Small – pale beardtongue
Penstemon palmeri A.Gray – Palmer's penstemon, Palmer penstemon
Penstemon papillatus J.T.Howell – Inyo beardtongue
Penstemon parryi A.Gray – Gray Parry penstemon, Parry's beardtongue
Penstemon parvulus (A.Gray) Krautter – Aquarius Plateau beardtongue
Penstemon parvus Pennell
Penstemon patens (M.E.Jones) N.H.Holmgren – Lone Pine beardtongue, Lone Pine penstemon
Penstemon payettensis A.Nelson & J.F.Macbr. – Payette beardtongue
Penstemon paysoniorum D.D.Keck – Payson's beardtongue
Penstemon peckii Pennell – Peck's beardtongue
Penstemon penlandii W.A.Weber – penland beardtongue, Penland's beardtongue
Penstemon pennellianus D.D.Keck – Blue Mountain beardtongue
Penstemon perfoliatus Al.Brongn.
Penstemon perpulcher A.Nelson – Minidoka beardtongue
Penstemon personatus D.D.Keck – closethroat beardtongue
Penstemon petiolatus Brandegee – lime penstemon, petiolate beardtongue
Penstemon pinifolius Greene – pineneedle beardtongue, pineneedle penstemon
Penstemon pinorum L.M.Shultz & J.S.Shultz – Pine Valley penstemon
Penstemon plagapineus Straw
Penstemon platyphyllus Rydb. – broadleaf beardtongue, broadleaf penstemon
Penstemon potosinus Straw
Penstemon pratensis Greene – whiteflower beardtongue, western whiteflower penstemon
Penstemon procerus Douglas ex Graham – littleflower penstemon, pincushion beardtongue
Penstemon pruinosus Douglas – Chelan beardtongue
Penstemon pseudoparvus Crosswh. – Mt. Washington beardtongue, San Mateo penstemon
Penstemon pseudoputus (Crosswh.) N.H.Holmgren – Kaibab Plateau beardtongue
Penstemon pseudospectabilis M.E.Jones – desert penstemon
Penstemon pudicus Reveal & Beatley – bashful penstemon, Kawich Range beardtongue
Penstemon pumilus Nutt. – Salmon River beardtongue
Penstemon punctatus Brandegee
Penstemon purpusii Brandegee – Snow Mountain beardtongue
Penstemon putus A.Nelson – Black River beardtongue
Penstemon radicosus A.Nelson – matroot penstemon
Penstemon rattanii A.Gray – Rattan's beardtongue
Penstemon richardsonii Douglas ex Lindl. – cutleaf beardtongue
Penstemon roezlii Regel – Roezl's penstemon
Penstemon roseus (Cerv. ex Sweet) G.Don
Penstemon rostriflorus Kellogg – beaked beardtongue, beakflower penstemon, Bridge penstemon
Penstemon rotundifolius A.Gray
Penstemon rubicundus D.D.Keck – Wassuck penstemon, Wassuk Range beardtongue
Penstemon rupicola (Piper) Howell – cliff beardtongue
Penstemon rydbergii A.Nelson – meadow beardtongue, Rydberg penstemon, Rydberg's penstemon
Penstemon saltarius Crosswh.
Penstemon saxosorum Pennell – upland beardtongue
Penstemon scapoides D.D.Keck – pinyon beardtongue
Penstemon scariosus Pennell – White River beardtongue
Penstemon schaffneri (Hemsl.) Straw
Penstemon secundiflorus Benth. – sidebells penstemon
Penstemon seorsus (A.Nelson) D.D.Keck – shortlobe penstemon
Penstemon sepalulus A.Nelson – littlecup beardtongue
Penstemon serrulatus Menzies ex Sm. – serrulate penstemon
Penstemon smallii A.Heller – Small's beardtongue
Penstemon spatulatus Pennell
Penstemon speciosus Douglas – prairie-clover, royal penstemon
Penstemon spectabilis Thurb. ex A.Gray – showy penstemon
Penstemon stenophyllus A.Gray – Sonoran beardtongue
Penstemon stephensii Brandegee – Stephens' penstemon
Penstemon strictiformis Rydb. – Mancos penstemon, stiff penstemon
Penstemon strictus Benth. – Rocky Mountain beardtongue, Rocky Mountain penstemon
Penstemon subglaber Rydb. – smooth penstemon
Penstemon subserratus Pennell – finetooth beardtongue
Penstemon subulatus M.E.Jones – hackberry beardtongue
Penstemon sudans M.E.Jones – Susanville beardtongue, Susanville penstemon
Penstemon superbus A.Nelson – superb beardtongue
Penstemon tenuiflorus Pennell – eastern whiteflower beardtongue
Penstemon tenuifolius Benth.
Penstemon tenuis Small – sharpsepal beardtongue
Penstemon tepicensis Straw
Penstemon teucrioides Greene – germander beardtongue
Penstemon thompsoniae (A.Gray) Rydb. – Thompson's penstemon, Thompson's beardtongue, Thompson penstemon
Penstemon thurberi Torr. – Thurber's penstemon, Thurber penstemon
Penstemon tidestromii Pennell – Tidestrom's beardtongue
Penstemon tracyi D.D.Keck – Trinity penstemon
Penstemon triflorus A.Heller – Heller's beardtongue
Penstemon triphyllus Douglas – Riggin's penstemon
Penstemon tubaeflorus Nutt. – white wand beardtongue
Penstemon uintahensis Pennell – Uinta Mountain beardtongue
Penstemon utahensis Eastw. – Utah penstemon
Penstemon venustus Douglas – Venus penstemon
Penstemon virens Pennell ex Rydb. – Front Range beardtongue
Penstemon virgatus A.Gray – upright blue beardtongue
Penstemon vizcainensis Moran
Penstemon vulcanellus Crosswh.
Penstemon wardii A.Gray – Ward's beardtongue
Penstemon washingtonensis D.D.Keck – Washington beardtongue
Penstemon watsonii A.Gray – Watson's penstemon, Watson's beardtongue, Watson penstemon
Penstemon wendtiorum B.L.Turner
Penstemon whippleanus A.Gray – dark beardtongue, Whipple's penstemon
Penstemon wilcoxii Rydb. – Wilcox's penstemon
Penstemon wislizeni (A.Gray) Straw
Penstemon wrightii Hook. – Wright's beardtongue
Penstemon yampaensis Penland – Yampa beardtongue
Natural hybrids
These five naturally occurring hybrids are valid according to WFO and POWO.
Penstemon × crideri A.Nelson – Crider penstemon, Crider's penstemon
Penstemon × dubius Davidson – dubius penstemon
Penstemon × mirus A.Nelson
Penstemon × parishii A.Gray
Penstemon × peirsonii Munz & I.M.Johnst.
Ambiguous species
These 35 species and two natural hybrids are of uncertain validity. Twenty-seven are recognized as valid by either WFO or POWO, but not both. The USDA Natural Resources Conservation Service PLANTS database (PLANTS) uses eight species not recognized by either WFO or POWO.
Penstemon alluviorum Pennell – lowland beardtongue
Penstemon angelicus (I.M.Johnst.) Moran
Penstemon brandegeei (Porter) Rydb.
Penstemon brevibarbatus Crosswhite
Penstemon bryantiae D.D. Keck
Penstemon cerrosensis Kellogg
Penstemon compactus (D.D.Keck) Crosswh. – compact penstemon
Penstemon curtiflorus (D.D.Keck) N.H.Holmgren
Penstemon dugesii Pérez-Calix & Zacarías
Penstemon grandiflorus Nutt. – large beardtongue, largeflowered penstemon
Penstemon hesperius M.E.Peck
Penstemon idahoensis N.D.Atwood & S.L.Welsh – Idaho beardtongue
Penstemon jaliscensis B.L.Rob.
Penstemon jonesii Pennell – Jones' penstemon
Penstemon laevigatus Soland.
Penstemon leptanthus Pennell – Sevier Plateau beardtongue
Penstemon minutifolius Straw
Penstemon moronensis Crosswh.
Penstemon parishii A.Gray – Parish's penstemon
Penstemon parviflorus Pennell – Montezuma County beardtongue
Penstemon reidmoranii Zacarías & A.Wolfe
Penstemon ramosus Crosswh. – lanceleaf beardtongue, lanceleaf penstemon
Penstemon retrorsoides Crosswh. – Adobe Hills beardtongue
Penstemon retrorsus Payson
Penstemon rhizomatosus N.H.Holmgren
Penstemon salmonensis N.H.Holmgren
Penstemon spathulatus Eastw. ex C.F.Baker – Wallowa beardtongue
Penstemon tiehmii N.H.Holmgren – Tiehm's beardtongue
Penstemon tubiflorus Nutt.
Penstemon tusharensis Penstemon tusharensis N.H.Holmgren – Tushar Range beardtongue
Penstemon unilateralis Rydb.
Penstemon versicolor Pennell
Penstemon xylus A.Nelson
Penstemon × jonesii Pennell
Penstemon × moronensis Crosswh.
See also
HMS Pentstemon
References
Further reading
Way, D. and P. James. The Gardener's Guide to Growing Penstemons. David & Charles Publishers. 1998.
Nold, Robert. Penstemons. Timber Press. 1999.
Lindgren, Dale T. Growing penstemons : species, cultivars, and hybrids. Haverford, PA: Infinity Pub. 2003. .
External links
American Penstemon Society
Wolfe Lab Penstemon Database
Medicinal plants
Plantaginaceae genera