| Penstemon abietinus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon aboriginum M.E.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon absarokensis Evert | Accepted |  | TRO |  | 
	
		| Penstemon acaulis L.O. Williams | Accepted |  | TRO |  | 
	
		| Penstemon acuminatus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon acuminatus var. congestus M.E. Jones | Synonym |  | TRO |  | 
	
		| Penstemon adamsianus Howell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon aggregatus Pennell | Synonym |  | TRO |  | 
	
		| Penstemon alamosensis Pennell & G.T. Nisbet | Accepted |  | TRO |  | 
	
		| Penstemon albertinus Greene | Accepted |  | TRO |  | 
	
		| Penstemon albidus Nutt. | Accepted |  | TRO |  | 
	
		| Penstemon albifloris England | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon albifluvis England | Accepted |  | TRO |  | 
	
		| Penstemon albomarginatus M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon albrightii A.Nelson & J.F.Macbr. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon albrightii A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon alluviorum Pennell | Accepted |  | TRO |  | 
	
		| Penstemon alpinus Torr. | Accepted |  | TRO |  | 
	
		| Penstemon alpinus subsp. brandegeei (Porter) Penland | Synonym |  | TRO |  | 
	
		| Penstemon alpinus subsp. magnus (Pennell) Penland | Accepted |  | TRO |  | 
	
		| Penstemon alpinus f. riparius (A. Nelson) Pennell | Accepted |  | TRO |  | 
	
		| Penstemon alsinoides Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon amabilis G.N.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon ambiguus Torr. | Accepted |  | TRO |  | 
	
		| Penstemon ambiguus var. thurberi (Torr.) A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon ammophilus N.H. Holmgren & L.M. Shultz | Accepted |  | TRO |  | 
	
		| Penstemon amoenus Kunze | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon amphorellae Crosswh. | Accepted |  | TRO |  | 
	
		| Penstemon amplexicaulis Moench | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon amplexicaulis Buckley | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon amplus A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon angelicus (I.M. Johnst.) Moran | Accepted |  | TRO |  | 
	
		| Penstemon anguineus Eastw. | Accepted |  | TRO |  | 
	
		| Penstemon angustifolius Nutt. ex Pursh | Accepted |  | TRO |  | 
	
		| Penstemon angustifolius var. angustifolius | Synonym |  | TRO |  | 
	
		| Penstemon angustifolius subsp. caudatus (A. Heller) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon angustifolius var. venosus (D.D. Keck) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon angustifolius subsp. venosus D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon antirrhinoides Benth. | Accepted |  | TRO |  | 
	
		| Penstemon antirrhinoides subsp. antirrhinoides | Synonym |  | TRO |  | 
	
		| Penstemon antirrhinoides var. microphyllus (A. Gray) Munz & I.M. Johnst. | Synonym |  | TRO |  | 
	
		| Penstemon apateticus Straw | Accepted |  | TRO |  | 
	
		| Penstemon apateticus subsp. townsendianus Straw | Synonym |  | TRO |  | 
	
		| Penstemon arenarius Greene | Accepted |  | TRO |  | 
	
		| Penstemon arenicola A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon argutus Paxton | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon aridus Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon arizonicus A.Heller | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon arkansanus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon assurgens D.D.Keck | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon atropurpureus (Sweet) G. Don | Accepted |  | TRO |  | 
	
		| Penstemon attenuatus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon attenuatus var. attenuatus | Synonym |  | TRO |  | 
	
		| Penstemon attenuatus subsp. attenuatus | Synonym |  | TRO |  | 
	
		| Penstemon attenuatus var. militaris (Greene) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon attenuatus var. palustris (Pennell) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon attenuatus var. pseudoprocerus (Rydb.) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon attenuatus var. varians A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon atwoodii S.L. Welsh | Accepted |  | TRO |  | 
	
		| Penstemon auriberbis Pennell | Accepted |  | TRO |  | 
	
		| Penstemon auricomus A.Nelson ex Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon auricomus A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon austinii Eastw. | Synonym |  | TRO |  | 
	
		| Penstemon australis Small | Accepted |  | TRO |  | 
	
		| Penstemon azureus Benth. | Accepted |  | TRO |  | 
	
		| Penstemon azureus subsp. azureus | Synonym |  | TRO |  | 
	
		| Penstemon azureus var. azureus | Synonym |  | TRO |  | 
	
		| Penstemon azureus var. parvulus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon azureus subsp. parvulus (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon baccharifolius Hook. | Accepted |  | TRO |  | 
	
		| Penstemon baccharifolius var. schaffneri Hemsl. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon bachimbensis Straw | Unresolved |  | TRO |  | 
	
		| Penstemon bakeri Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon barbatus (Cav.) Roth | Accepted |  | TRO |  | 
	
		| Penstemon barbatus var. barbatus | Synonym |  | TRO |  | 
	
		| Penstemon barbatus var. labrosus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon barbatus subsp. torreyi (Benth.) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon barbatus subsp. trichander (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon barbatus var. wislizeni A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon barnebyi N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon barrettiae A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon berryi Eastw. | Synonym |  | TRO |  | 
	
		| Penstemon bicolor (Brandegee) Clokey & D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon bolanus Straw | Accepted |  | TRO |  | 
	
		| Penstemon brachyanthus Pennell | Synonym |  | TRO |  | 
	
		| Penstemon bracteatus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon bradburyi Pursh | Accepted |  | TRO |  | 
	
		| Penstemon brandegeei (Porter) Rydb. | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon brevibarbatus Crosswhite | Accepted |  | TRO |  | 
	
		| Penstemon breviculus (D.D. Keck) G.T. Nisbet & R.C. Jacks. | Accepted |  | TRO |  | 
	
		| Penstemon breviflorus Lindl. | Synonym |  | TRO |  | 
	
		| Penstemon brevifolius (A. Gray) A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon brevilabris A.Gray | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon brevis A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon brevisepalus Pennell | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon brevisepalus f. brevisepalus | Synonym |  | TRO |  | 
	
		| Penstemon bridgesii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon brittoniorum Pennell | Accepted |  | TRO |  | 
	
		| Penstemon brittonoruro Pennell ex Peattie | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon × bryantiae D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon buckleyi Pennell | Accepted |  | TRO |  | 
	
		| Penstemon cacuminis Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon caelestinus Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon caeruleum Nutt. | Synonym |  | TRO |  | 
	
		| Penstemon caeruleus Bailly | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon caesius A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon caespitosus Nutt. ex A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon caespitosus var. caespitosus | Synonym |  | TRO |  | 
	
		| Penstemon caespitosus var. desertipicti (A. Nelson) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon caespitosus var. suffruticosus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon caespitosus subsp. suffruticosus (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon calcareus Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon californicus (Munz & I.M. Johnst.) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon calycosus Small | Accepted |  | TRO |  | 
	
		| Penstemon campanulatus (Cav.) Willd. | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon campanulatus var. chihuahuensis (Straw) B.L. Turner | Accepted |  | TRO |  | 
	
		| Penstemon campanulatus subsp. chihuahuensis Straw | Synonym |  | TRO |  | 
	
		| Penstemon canescens (Britton) Britton | Accepted |  | TRO |  | 
	
		| Penstemon canescens f. brittoniorum (Pennell) Fernald | Accepted |  | TRO |  | 
	
		| Penstemon canescens subsp. brittoniorum (Pennell) Pennell | Synonym |  | TRO |  | 
	
		| Penstemon canescens f. canescens | Synonym |  | TRO |  | 
	
		| Penstemon canosobarbatum Kellogg | Unresolved |  | TRO |  | 
	
		| Penstemon cardinalis Wooton & Standl. | Accepted |  | TRO |  | 
	
		| Penstemon cardinalis subsp. regalis (A. Nelson) G.T. Nisbet & R.C. Jacks. | Accepted |  | TRO |  | 
	
		| Penstemon cardwellii Howell | Accepted |  | TRO |  | 
	
		| Penstemon carinatus Kellogg | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon carnosus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon caryi Pennell | Accepted |  | TRO |  | 
	
		| Penstemon caudatus A. Heller | Synonym |  | TRO |  | 
	
		| Penstemon cedrosensis Krautter | Accepted |  | TRO |  | 
	
		| Penstemon centranthifolius (Benth.) Benth. | Accepted |  | TRO |  | 
	
		| Penstemon cephalanthus Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cephalophorus Greene | Synonym |  | TRO |  | 
	
		| Penstemon cerrosensis Kellogg | Accepted |  | TRO |  | 
	
		| Penstemon chionophilus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon chionophilus Greene ex C.F.Baker | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cinerascens Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cinerascens Greene ex C.F.Baker | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cinereus Piper | Accepted |  | TRO |  | 
	
		| Penstemon cinereus subsp. cinereus | Synonym |  | TRO |  | 
	
		| Penstemon cinicola D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon cleburnei M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon clevelandii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon clevelandii var. angelicus I.M. Johnst. | Synonym |  | TRO |  | 
	
		| Penstemon clevelandii subsp. clevelandii | Synonym |  | TRO |  | 
	
		| Penstemon clevelandii subsp. connatus (Munz & I.M. Johnst.) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon clevelandii var. connatus Munz & I.M. Johnst. | Synonym |  | TRO |  | 
	
		| Penstemon clutei A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon cobaea Nutt. | Accepted |  | TRO |  | 
	
		| Penstemon cobaea var. purpureus Pennell | Synonym |  | TRO |  | 
	
		| Penstemon cobaea subsp. purpureus (Pennell) Pennell | Accepted |  | TRO |  | 
	
		| Penstemon coccinatus Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon coccineus Engelm. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon coeruleus Torr. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon coeruleus Nutt. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon collinus A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon coloradoensis A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon coloradoensis subsp. sileri (A. Gray) Pennell | Synonym |  | TRO |  | 
	
		| Penstemon colvillii Huber | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon comarrhenus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon compactus (D.D. Keck) Crosswh. | Accepted |  | TRO |  | 
	
		| Penstemon concinnus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon confertus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon confertus var. aberrans M.E. Jones | Synonym |  | TRO |  | 
	
		| Penstemon confertus var. attenuatus (Douglas ex Lindl.) M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon confertus var. geniculatus (Greene) Jeps. | Accepted |  | TRO |  | 
	
		| Penstemon confertus var. globosus Piper | Synonym |  | TRO |  | 
	
		| Penstemon confertus var. modestus (Greene) Jeps. | Synonym |  | TRO |  | 
	
		| Penstemon confusus M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon confusus var. patens M.E. Jones | Synonym |  | TRO |  | 
	
		| Penstemon congestus (M.E. Jones) Pennell | Synonym |  | TRO |  | 
	
		| Penstemon connatifolius A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon connatus Deppe | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cordatus M.Martens & Galeotti | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cordatus Walp. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cordifolius Benth. | Accepted |  | TRO |  | 
	
		| Penstemon corymbosus Benth. | Accepted |  | TRO |  | 
	
		| Penstemon crandallii A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon crandallii var. crandallii | Synonym |  | TRO |  | 
	
		| Penstemon crandallii subsp. glabrescens (Pennell) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon crandallii subsp. procumbens (Greene) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon crandallii var. taosensis (D.D. Keck) G.T. Nisbet & R.C. Jacks. | Accepted |  | TRO |  | 
	
		| Penstemon crassifolius Lindl. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon crassifolius Shuttlew. ex Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon crassulus Wooton & Standl. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon × crideri A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon cristatus Nutt. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon cusickii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon cyananthus Hook. | Accepted |  | TRO |  | 
	
		| Penstemon cyananthus var. brandegeei Porter | Synonym |  | WCSP (in review) |  | 
	
		| Penstemon cyananthus var. cyananthus | Synonym |  | TRO |  | 
	
		| Penstemon cyananthus subsp. longiflorus Pennell | Synonym |  | TRO |  | 
	
		| Penstemon cyananthus var. subglaber (A. Gray) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon cyaneus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon cyanocaulis Payson | Accepted |  | TRO |  | 
	
		| Penstemon cyathophorus Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon dasyphyllus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon davidsonii Greene | Accepted |  | TRO |  | 
	
		| Penstemon davidsonii var. davidsonii | Synonym |  | TRO |  | 
	
		| Penstemon dayanus Howell | Synonym |  | TRO |  | 
	
		| Penstemon deamii Pennell | Accepted |  | TRO |  | 
	
		| Penstemon deaveri Crosswh. | Accepted |  | TRO |  | 
	
		| Penstemon debilis O'Kane & J.L. Anderson | Accepted |  | TRO |  | 
	
		| Penstemon decurvus Pennell ex Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon degeneri Crosswh. | Accepted |  | TRO |  | 
	
		| Penstemon depressus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon deserticola Piper | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon desertipicti A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon desertorum M.E.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon deustus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon deustus var. deustus | Synonym |  | TRO |  | 
	
		| Penstemon deustus subsp. deustus | Synonym |  | TRO |  | 
	
		| Penstemon deustus var. heterander (Torr. & A. Gray) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon diffusus Douglas | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon digitalis Nutt. ex Sims | Accepted |  | TRO |  | 
	
		| Penstemon digitalis var. attenuatus (Douglas ex Lindl.) Trautv. | Synonym |  | TRO |  | 
	
		| Penstemon digitalis var. gracilis (Nutt.) Trautv. | Synonym |  | TRO |  | 
	
		| Penstemon dimorphus Kuntze | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon diphyllus Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon discolor D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon dissectus Elliott | Accepted |  | TRO |  | 
	
		| Penstemon distans N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon divergens M.E.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon dolius M.E. Jones ex Pennell | Accepted |  | TRO |  | 
	
		| Penstemon dolius var. dolius | Synonym |  | TRO |  | 
	
		| Penstemon douglasii Hook. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon × dubius Davidson | Unresolved |  | TRO |  | 
	
		| Penstemon duchesnensis (N.H. Holmgren) Neese | Accepted |  | TRO |  | 
	
		| Penstemon eastwoodiae A.Heller | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon eatonii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon eatonii subsp. eatonii | Synonym |  | TRO |  | 
	
		| Penstemon eatonii var. eatonii | Synonym |  | TRO |  | 
	
		| Penstemon eatonii subsp. exsertus (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon × edithae English | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon elegans Poir. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon elegantulus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon ellipticus J.M. Coult. & Fisher | Accepted |  | TRO |  | 
	
		| Penstemon erianthera Fraser ex Nutt. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon eriantherus Pursh | Accepted |  | TRO |  | 
	
		| Penstemon eriantherus var. eriantherus | Synonym |  | TRO |  | 
	
		| Penstemon eriantherus subsp. saliens (Rydb.) Pennell | Accepted |  | TRO |  | 
	
		| Penstemon eriantherus var. whitedii (Piper) A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon erosus Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon euglaucus English | Accepted |  | TRO |  | 
	
		| Penstemon exilifolius A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon eximius D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon exsertus A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon fasciculatus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon fendleri Torr. & A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon filifolius Nutt. ex Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon filiformis (D.D. Keck) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon filisepalis Straw | Accepted |  | TRO |  | 
	
		| Penstemon flavescens Pennell | Accepted |  | TRO |  | 
	
		| Penstemon flaviflorus M.E.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon floribundus Danley | Accepted |  | TRO |  | 
	
		| Penstemon floridus Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon floridus var. austinii (Eastw.) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon floridus subsp. floridus | Synonym |  | TRO |  | 
	
		| Penstemon floridus var. floridus | Synonym |  | TRO |  | 
	
		| Penstemon flowersii Neese & S.L. Welsh | Accepted |  | TRO |  | 
	
		| Penstemon formosus A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon francisci-pennellii Crosswh. | Synonym |  | TRO |  | 
	
		| Penstemon franklinii S.L.Welsh | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon fremontii Torr. & A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon fremontii var. subglaber A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon frutescens Lamb. | Synonym |  | TRO |  | 
	
		| Penstemon fruticiformis Coville | Accepted |  | TRO |  | 
	
		| Penstemon fruticiformis subsp. fruticiformis | Synonym |  | TRO |  | 
	
		| Penstemon fruticiformis var. fruticiformis | Synonym |  | TRO |  | 
	
		| Penstemon fruticosus (Pursh) Greene | Accepted |  | TRO |  | 
	
		| Penstemon fruticosus var. fruticosus | Synonym |  | TRO |  | 
	
		| Penstemon fruticosus subsp. fruticosus | Synonym |  | TRO |  | 
	
		| Penstemon fruticosus var. scouleri (Lindl.) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon gairdneri Hook. | Accepted |  | TRO |  | 
	
		| Penstemon gairdneri var. gairdneri | Synonym |  | TRO |  | 
	
		| Penstemon gairdneri subsp. gairdneri | Synonym |  | TRO |  | 
	
		| Penstemon gairdneri subsp. hians (Piper) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon gairdneri var. hians Piper | Synonym |  | TRO |  | 
	
		| Penstemon gairdneri subsp. oreganus (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon galloensis G.L. Nesom | Accepted |  | TRO |  | 
	
		| Penstemon garrettii Pennell | Synonym |  | WCSP (in review) |  | 
	
		| Penstemon geniculatus Greene | Synonym |  | TRO |  | 
	
		| Penstemon gentianoides (Kunth) Poir. | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon gentryi Standl. | Accepted |  | TRO |  | 
	
		| Penstemon gibbensii Dorn | Accepted |  | TRO |  | 
	
		| Penstemon giganteus C.Morren | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon glaber Pursh | Accepted |  | TRO |  | 
	
		| Penstemon glaber var. brandegeei (Porter) C.C. Freeman | Synonym |  | TRO |  | 
	
		| Penstemon glaber var. glaber | Synonym |  | TRO |  | 
	
		| Penstemon glaberrimus Bevis ex W.H.Baxter | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon glabrescens Pennell | Synonym |  | TRO |  | 
	
		| Penstemon glandulosus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon glandulosus subsp. glandulosus | Synonym |  | TRO |  | 
	
		| Penstemon glastifolius Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon glaucifolius A.Gray | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon glaucinus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon glaucophyllus Scheele | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon glaucus Graham | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon glaucus var. stenosepalus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon globosus (Piper) Pennell & see Keck, David Daniels | Accepted |  | TRO |  | 
	
		| Penstemon gloxinioides hort. | Unresolved |  | TRO |  | 
	
		| Penstemon goodrichii N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon gordonianus A.Gray | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon gordonii Hook. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon gormanii Greene | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon gormanii f. gormanii | Synonym |  | TRO |  | 
	
		| Penstemon gracilentus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon gracilis Nutt. | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon gracilis var. gracilis | Synonym |  | TRO |  | 
	
		| Penstemon gracilis var. wisconsinensis (Pennell) Fassett | Accepted |  | TRO |  | 
	
		| Penstemon grahamii D.D. Keck ex E.H. Graham | Accepted |  | TRO |  | 
	
		| Penstemon grandiflorus Nutt. | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon griffinii A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon grinnellii Eastw. | Accepted |  | TRO |  | 
	
		| Penstemon grinnellii subsp. grinnellii | Synonym |  | TRO |  | 
	
		| Penstemon grinnellii var. grinnellii | Synonym |  | TRO |  | 
	
		| Penstemon grinnellii var. scrophularioides (M.E. Jones) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon guadalupensis A. Heller | Accepted |  | TRO |  | 
	
		| Penstemon guadalupensis subsp. ernestii Pennell | Synonym |  | TRO |  | 
	
		| Penstemon guadalupensis var. ernestii (Pennell) Cory | Accepted |  | TRO |  | 
	
		| Penstemon hallii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon hallii var. arizonicus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon hansonii A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon harbourii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon harringtonii Penland | Accepted |  | TRO |  | 
	
		| Penstemon hartwegii Benth. | Accepted |  | TRO |  | 
	
		| Penstemon havardii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon haydenii S. Watson | Accepted |  | TRO |  | 
	
		| Penstemon helleri Small | Accepted |  | TRO |  | 
	
		| Penstemon henricksonii Straw | Accepted |  | TRO |  | 
	
		| Penstemon hesperius M. Peck | Accepted |  | TRO |  | 
	
		| Penstemon heterander Torr. & A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon heterodoxus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon heterodoxus var. cephalophorus (Greene) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon heterodoxus subsp. heterodoxus | Synonym |  | TRO |  | 
	
		| Penstemon heterodoxus var. heterodoxus | Synonym |  | TRO |  | 
	
		| Penstemon heterophyllus Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon heterophyllus subsp. heterophyllus | Synonym |  | TRO |  | 
	
		| Penstemon heterophyllus var. heterophyllus | Synonym |  | TRO |  | 
	
		| Penstemon heterophyllus subsp. spinulosus (Wooton & Standl.) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon hians I.M.Johnst. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon hidalgensis Straw | Accepted |  | TRO |  | 
	
		| Penstemon higginsii (Neese) N.H. Holmgren & N.D. Atwood | Accepted |  | TRO |  | 
	
		| Penstemon hintonii Straw | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon hirsutus (L.) Willd. | Accepted |  | TRO |  | 
	
		| Penstemon holmgrenii S.L.Clark | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon humboldtii G.Don | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon humilis Nutt. ex A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon humilis subsp. brevifolius (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon humilis var. humilis | Synonym |  | TRO |  | 
	
		| Penstemon humilis var. obtusifolius (Pennell) Reveal | Accepted |  | TRO |  | 
	
		| Penstemon × hybridus Voss | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon idahoensis N.D.Atwood & S.L.Welsh | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon ilicifolius Nutt. ex Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon imberbis (Kunth) Trautv. | Accepted |  | TRO |  | 
	
		| Penstemon immanifestus N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon incanus (A. Gray) Tidestr. | Accepted |  | TRO |  | 
	
		| Penstemon incertus Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon inermis Poir. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon inflatus Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon interruptus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon intonsus A.Heller | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon isophyllus B.L. Rob. | Accepted |  | TRO |  | 
	
		| Penstemon jacintensis Abrams | Synonym |  | TRO |  | 
	
		| Penstemon jaffrayanus Hook. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon jaffrayanus var. parvulus (A. Gray) Jeps. | Synonym |  | TRO |  | 
	
		| Penstemon jaliscensis B.L. Rob. | Accepted |  | TRO |  | 
	
		| Penstemon jamesii Benth. | Accepted |  | TRO |  | 
	
		| Penstemon jamesii subsp. breviculus D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon janishiae N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon jeffreyanus A.Murray bis | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon jonesii Pennell | Accepted |  | TRO |  | 
	
		| Penstemon keckii Clokey | Accepted |  | TRO |  | 
	
		| Penstemon kennedyi A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon kingii S. Watson | Accepted |  | TRO |  | 
	
		| Penstemon kleei Greene | Synonym |  | TRO |  | 
	
		| Penstemon kunthii G. Don | Accepted |  | TRO |  | 
	
		| Penstemon labrosus (A. Gray) Mast. ex Hook. f. | Accepted |  | TRO |  | 
	
		| Penstemon lacerellus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon laetus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon laetus subsp. filiformis D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon laetus var. filiformis (D.D. Keck) McMinn | Synonym |  | TRO |  | 
	
		| Penstemon laetus subsp. laetus | Synonym |  | TRO |  | 
	
		| Penstemon laetus var. laetus | Synonym |  | TRO |  | 
	
		| Penstemon laevigatus Soland. | Accepted |  | TRO |  | 
	
		| Penstemon laevigatus Aiton | Unresolved |  | TRO |  | 
	
		| Penstemon laevigatus var. calycosus (Small) Farw. | Synonym |  | TRO |  | 
	
		| Penstemon laevigatus subsp. calycosus (Small) R.W. Benn. | Accepted |  | TRO |  | 
	
		| Penstemon laevigatus var. canescens Britton | Synonym |  | TRO |  | 
	
		| Penstemon laevis Pennell | Accepted |  | TRO |  | 
	
		| Penstemon lanceolatus Benth. | Accepted |  | TRO |  | 
	
		| Penstemon laricifolius Hook. & Arn. | Accepted |  | TRO |  | 
	
		| Penstemon laricifolius subsp. exilifolius (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon laricifolius var. exilifolius (A. Nelson) Payson | Synonym |  | TRO |  | 
	
		| Penstemon lassenianus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon latifolius Hoffmanns. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon latifolius Krautter | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon latiusculus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon laxiflorus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon laxus A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon leiophyllus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon leiophyllus var. francisci-pennellii (Crosswh.) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon leiophyllus var. leiophyllus | Synonym |  | TRO |  | 
	
		| Penstemon lemhiensis (D.D. Keck) D.D. Keck & Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon lemmonii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon lentus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon lentus var. lentus | Synonym |  | TRO |  | 
	
		| Penstemon leonardii Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon leonensis Straw | Accepted |  | TRO |  | 
	
		| Penstemon leptanthus Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon leptophyllus Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon leucanthus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon lewisii Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon linarioides A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon linarioides var. californicus Munz & I.M. Johnst. | Synonym |  | TRO |  | 
	
		| Penstemon linarioides subsp. coloradoensis (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon linarioides var. seorsus A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon linarioides subsp. sileri (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon linarioides subsp. taosensis D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon linearifolius J.M.Coult. & Fisher | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon lineolatus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon lobbii Lem. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon longiflorus (Pennell) S.L. Clark | Accepted |  | TRO |  | 
	
		| Penstemon longifolius Scheele | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon luteus G.L. Nesom | Accepted |  | TRO |  | 
	
		| Penstemon lyallii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon macbridei A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon × macewanii Paxton | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon mackayanus Knowles & Westc. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon macranthus Eastw. | Synonym |  | TRO |  | 
	
		| Penstemon magnus Pennell | Synonym |  | TRO |  | 
	
		| Penstemon maguirei Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon marcusii (D.D. Keck) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon mensarum Pennell | Accepted |  | TRO |  | 
	
		| Penstemon menziesii Hook. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon menziesii subsp. davidsonii (Greene) Piper | Unresolved |  | TRO |  | 
	
		| Penstemon menziesii var. davidsonii (Greene) Piper | Synonym |  | TRO |  | 
	
		| Penstemon metcalfei Wooton & Standl. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon mexicanus Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon micranthus Nutt. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon micranthus Torr. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon microphyllus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon militaris Greene | Synonym |  | TRO |  | 
	
		| Penstemon miniatus Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon miniatus subsp. miniatus | Synonym |  | TRO |  | 
	
		| Penstemon miniatus var. townsendianus (Straw) C.C.Freeman | Accepted |  | TRO |  | 
	
		| Penstemon minidokanus A.Nelson & J.F.Macbr. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon minor (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon minutifolius Straw | Accepted |  | TRO |  | 
	
		| Penstemon × mirus A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon miser A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon modestus Greene | Synonym |  | TRO |  | 
	
		| Penstemon moffatii Eastw. | Accepted |  | TRO |  | 
	
		| Penstemon moffatii subsp. marcusii D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon moffatii subsp. paysonii (Pennell) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon mohinoranus Straw | Accepted |  | TRO |  | 
	
		| Penstemon monoensis A. Heller | Accepted |  | TRO |  | 
	
		| Penstemon montanus Greene | Accepted |  | TRO |  | 
	
		| Penstemon montanus var. montanus | Synonym |  | TRO |  | 
	
		| Penstemon moriahensis N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon moronensis Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon mucronatus N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon multicaulis Pennell | Accepted |  | TRO |  | 
	
		| Penstemon multiflorus (Benth.) Chapm. ex Small | Accepted |  | TRO |  | 
	
		| Penstemon munzii I.M.Johnst. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon murrayanus Hook. | Accepted |  | TRO |  | 
	
		| Penstemon nanus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon navajoa N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon nelsoniae D.D.Keck & Thomps. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon nemorosus (Douglas ex Lindl.) Trautv. | Synonym |  | WCSP (in review) |  | 
	
		| Penstemon neomexicanus Wooton & Standl. | Accepted |  | TRO |  | 
	
		| Penstemon neotericus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon newberryi A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon newberryi var. berryi (Eastw.) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon newberryi subsp. newberryi | Synonym |  | TRO |  | 
	
		| Penstemon newberryi var. newberryi | Synonym |  | TRO |  | 
	
		| Penstemon newberryi var. rupicola Piper | Synonym |  | TRO |  | 
	
		| Penstemon newberryi subsp. sonomensis (Greene) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon nitidus Douglas ex Benth. | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon nitidus var. nitidus | Synonym |  | TRO |  | 
	
		| Penstemon nudiflorus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon nuttallii L.C.Beck | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon nyeensis Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon obtusifolius Pennell | Synonym |  | TRO |  | 
	
		| Penstemon occiduus Straw | Accepted |  | TRO |  | 
	
		| Penstemon oklahomensis Pennell | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon oliganthus Wooton & Standl. | Accepted |  | TRO |  | 
	
		| Penstemon ophianthus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon oreganus (A. Gray) Howell | Synonym |  | TRO |  | 
	
		| Penstemon oregonensis A.Murray bis | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon oreocharis Greene | Accepted |  | TRO |  | 
	
		| Penstemon oreophilus Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon osterhoutii Pennell | Accepted |  | TRO |  | 
	
		| Penstemon ovatus Douglas | Accepted |  | TRO |  | 
	
		| Penstemon ovatus var. ovatus | Synonym |  | TRO |  | 
	
		| Penstemon owenii A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pachyphyllus A. Gray ex Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon pachyphyllus var. congestus (M.E. Jones) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon pachyphyllus var. pachyphyllus | Synonym |  | TRO |  | 
	
		| Penstemon pahutensis N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon pallescens Osterh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pallidus Small | Accepted |  | TRO |  | 
	
		| Penstemon palmeri A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon palmeri var. bicolor Brandegee | Synonym |  | TRO |  | 
	
		| Penstemon palmeri var. macranthus (Eastw.) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon palmeri var. palmeri | Synonym |  | TRO |  | 
	
		| Penstemon palustris Pennell | Synonym |  | TRO |  | 
	
		| Penstemon pandus (A. Nelson & J.F. Macbr.) A. Nelson & J.F. Macbr. | Accepted |  | TRO |  | 
	
		| Penstemon paniculatus Howell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon papillatus J.T. Howell | Accepted |  | TRO |  | 
	
		| Penstemon parishii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon × parishii A. Gray | Unresolved |  | TRO |  | 
	
		| Penstemon parryi (A. Gray) A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon parviflorus Pennell | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon parvulus (A. Gray) Krautter | Accepted |  | TRO |  | 
	
		| Penstemon parvus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon patens (M.E. Jones) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon patricus N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon pauciflorus Buckley | Accepted |  | TRO |  | 
	
		| Penstemon payettensis A. Nelson & J.F. Macbr. | Accepted |  | TRO |  | 
	
		| Penstemon paysonii Pennell | Synonym |  | TRO |  | 
	
		| Penstemon paysoniorum D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon peckii Pennell | Accepted |  | TRO |  | 
	
		| Penstemon peduncularis Nutt. ex Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon × peirsonii Munz & I.M. Johnst. | Unresolved |  | TRO |  | 
	
		| Penstemon penlandii W.A. Weber | Accepted |  | TRO |  | 
	
		| Penstemon pennellianus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon pentstemon (L.) MacMill. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon perfoliatus Brongn. | Accepted |  | TRO |  | 
	
		| Penstemon perpulcher A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon perpulcher var. pandus A. Nelson & J.F. Macbr. | Synonym |  | TRO |  | 
	
		| Penstemon personatus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon petiolatus Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon phlogifolius Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pickettii H.St.John | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pilifer A. Heller | Synonym |  | TRO |  | 
	
		| Penstemon piliferus A.Heller | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pilosigulatus A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pinetorum Piper | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pinifolius Greene | Accepted |  | TRO |  | 
	
		| Penstemon pinorum L. Shultz & J. Shultz | Accepted |  | TRO |  | 
	
		| Penstemon plagapineus Straw | Accepted |  | TRO |  | 
	
		| Penstemon platyphyllus Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon plummerae Abrams | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pononii auct. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon potosinus Straw | Accepted |  | TRO |  | 
	
		| Penstemon pratensis Greene | Accepted |  | TRO |  | 
	
		| Penstemon pringlei S.Watson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon procerus Douglas ex Graham | Accepted |  | TRO |  | 
	
		| Penstemon procerus subsp. aberrans (M.E. Jones) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon procerus var. brachyanthus (Pennell) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon procerus var. formosus (A. Nelson) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon procerus f. genuiculatus (Greene) L. Clark | Synonym |  | TRO |  | 
	
		| Penstemon procerus var. modestus (Greene) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon procerus var. procerus | Synonym |  | TRO |  | 
	
		| Penstemon procerus f. procerus | Synonym |  | TRO |  | 
	
		| Penstemon procerus var. tolmiei (Hook.) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon procerus subsp. tolmiei (Hook.) D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon procumbens Greene | Synonym |  | TRO |  | 
	
		| Penstemon productus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon propinquus Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pruinosus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon pseudohumilis M.E.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pseudohumilis Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pseudoparvus Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pseudoprocerus Rydb. | Synonym |  | TRO |  | 
	
		| Penstemon pseudoputus (Crosswh.) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon pseudospectabilis M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon pseudospectabilis subsp. bicolor (Brandegee) D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon pseudospectabilis subsp. clutei (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon pseudospectabilis subsp. connatifolius (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon pseudospectabilis subsp. pseudospectabilis | Synonym |  | TRO |  | 
	
		| Penstemon puberulentus Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon puberulus Wooton & Standl. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon puberulus M.E.Jones | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pubescens Aiton | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon pubescens var. gracilis (Nutt.) A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon pubescens var. multiflorus Benth. | Synonym |  | TRO |  | 
	
		| Penstemon pudicus Reveal & Beatley | Accepted |  | TRO |  | 
	
		| Penstemon pulchellus Lindl. | Synonym |  | WCSP (in review) |  | 
	
		| Penstemon pumilus Nutt. | Accepted |  | TRO |  | 
	
		| Penstemon pumilus var. incanus A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon pumilus var. thompsoniae A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon punctatus Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon puniceus Lilja | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon puniceus A.Gray | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon puniceus var. parryi A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon purpusii Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon putus A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon radicosus A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon ramaleyi A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon ramosus Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon rattanii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon rattanii subsp. kleei (Greene) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon rattanii var. minor A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon rattanii subsp. rattanii | Synonym |  | TRO |  | 
	
		| Penstemon rattanii var. rattanii | Synonym |  | TRO |  | 
	
		| Penstemon recurvatus A.Heller | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon regalis A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon retrorsoides Crosswh. | Unresolved |  | TRO |  | 
	
		| Penstemon retrorsus Payson ex Pennell | Accepted |  | TRO |  | 
	
		| Penstemon rex A.Nelson & J.F.Macbr. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon rhizomatosus N.H.Holmgren | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon richardsonii Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon richardsonii var. richardsonii | Synonym |  | TRO |  | 
	
		| Penstemon riparius A. Nelson | Synonym |  | TRO |  | 
	
		| Penstemon rivularis Douglas ex Trautv. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon roezlii Regel | Accepted |  | TRO |  | 
	
		| Penstemon roezlii var. violaceus Brandegee | Synonym |  | TRO |  | 
	
		| Penstemon roseus (Cerv. ex Sweet) G. Don | Accepted |  | TRO |  | 
	
		| Penstemon rostriflorus Kellogg | Accepted |  | TRO |  | 
	
		| Penstemon rothrockii A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon rothrockii var. jacintensis (Abrams) Munz & I.M. Johnst. | Synonym |  | TRO |  | 
	
		| Penstemon rotundifolius A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon rubescens A.Gray | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon rubicundus D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon rupicola (Piper) Howell | Accepted |  | TRO |  | 
	
		| Penstemon rydbergii A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon rydbergii var. aggregatus (Pennell) N.H. Holmgren | Accepted |  | TRO |  | 
	
		| Penstemon rydbergii subsp. aggregatus (Pennell) D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon rydbergii var. rydbergii | Synonym |  | TRO |  | 
	
		| Penstemon rydbergii var. varians (A. Nelson) Cronquist | Accepted |  | TRO |  | 
	
		| Penstemon sagittatus (D.D.Keck) Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon saliens Rydb. | Synonym |  | TRO |  | 
	
		| Penstemon saltarius Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon saxosorum Pennell | Accepted |  | TRO |  | 
	
		| Penstemon scabridus Eastw. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon scapoides D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon scariosus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon scariosus var. garrettii (Pennell) N.H.Holmgren | Accepted |  | WCSP (in review) |  | 
	
		| Penstemon scariosus var. scariosus | Synonym |  | TRO |  | 
	
		| Penstemon schaffneri (Hemsl.) Straw | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon scoparius A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon scouleri Lindl. | Synonym |  | TRO |  | 
	
		| Penstemon scrophularioides M.E. Jones | Synonym |  | TRO |  | 
	
		| Penstemon secundiflorus Benth. | Accepted |  | TRO |  | 
	
		| Penstemon seorsus (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon sepalulus A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon serrulatus Menzies ex Sm. | Accepted |  | TRO |  | 
	
		| Penstemon shantzii A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon shastensis D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon shockleyi S.Watson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon similis A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon skutchii Straw | Synonym |  | WCSP (in review) |  | 
	
		| Penstemon smallii A. Heller | Accepted |  | TRO |  | 
	
		| Penstemon sonomensis Greene | Synonym |  | TRO |  | 
	
		| Penstemon spathulatus Eastw. ex C.F.Baker | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon spatulatus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon speciosus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon speciosus subsp. kennedyi (A. Nelson) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon speciosus subsp. lemhiensis D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon speciosus var. piliferus (A. Heller) Munz & I.M. Johnst. | Accepted |  | TRO |  | 
	
		| Penstemon speciosus subsp. speciosus | Synonym |  | TRO |  | 
	
		| Penstemon spectabilis Thurb. ex A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon spectabilis subsp. spectabilis | Synonym |  | TRO |  | 
	
		| Penstemon spectabilis var. spectabilis | Synonym |  | TRO |  | 
	
		| Penstemon spicatus auct. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon spinulosus Wooton & Standl. | Synonym |  | TRO |  | 
	
		| Penstemon staticifolius Lindl. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon stenophyllus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon stenosepalus (A. Gray) Howell | Accepted |  | TRO |  | 
	
		| Penstemon stephensii Brandegee | Accepted |  | TRO |  | 
	
		| Penstemon strictiformis Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon strictus Benth. | Accepted |  | TRO |  | 
	
		| Penstemon subglaber Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon subserratus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon subulatus M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon sudans M.E. Jones | Accepted |  | TRO |  | 
	
		| Penstemon suffrutescens Rydb. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon suffruticosus Douglas ex Benth. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon superbus A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tenellus Kellogg | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tenuiflorus Pennell | Accepted |  | TRO |  | 
	
		| Penstemon tenuifolius Benth. | Accepted |  | TRO |  | 
	
		| Penstemon tenuis Small | Accepted |  | TRO |  | 
	
		| Penstemon tepicensis Straw | Accepted |  | TRO |  | 
	
		| Penstemon teretiflorus Nutt. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon ternatus Torr. ex A. Gray | Synonym |  | TRO |  | 
	
		| Penstemon ternatus var. septentrionalis Munz & I.M. Johnst. | Synonym |  | TRO |  | 
	
		| Penstemon teucrioides Greene | Accepted |  | TRO |  | 
	
		| Penstemon themisteri Bailly | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon thompsoniae (A. Gray) Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon thurberi Torr. | Accepted |  | TRO |  | 
	
		| Penstemon tidestromii Pennell | Accepted |  | TRO |  | 
	
		| Penstemon tiehmii N.H.Holmgren | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tinctus Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tolmiei Hook. | Synonym |  | TRO |  | 
	
		| Penstemon tolmiei subsp. modestus (Greene) D.D. Keck | Synonym |  | TRO |  | 
	
		| Penstemon torreyi Benth. | Synonym |  | TRO |  | 
	
		| Penstemon tracyi D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon trichander (A. Gray) Rydb. | Synonym |  | TRO |  | 
	
		| Penstemon triflorus A. Heller | Accepted |  | TRO |  | 
	
		| Penstemon triphyllus Douglas | Accepted |  | TRO |  | 
	
		| Penstemon truncatus Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tubaeflorus Nutt. | Accepted |  | TRO |  | 
	
		| Penstemon tubaeflorus var. tubaeflorus | Synonym |  | TRO |  | 
	
		| Penstemon tubiflorus Nutt. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tusharensis N.H.Holmgren | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon tweedyi Canby & Rose | Synonym |  | TRO |  | 
	
		| Penstemon uintahensis Pennell | Accepted |  | TRO |  | 
	
		| Penstemon unilateralis Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon utahensis Eastw. | Accepted |  | TRO |  | 
	
		| Penstemon variabilis Suksd. | Accepted |  | TRO |  | 
	
		| Penstemon vaseyanus Greene | Accepted |  | TRO |  | 
	
		| Penstemon venosus (D.D. Keck) Reveal | Synonym |  | TRO |  | 
	
		| Penstemon venustus Douglas ex Lindl. | Accepted |  | TRO |  | 
	
		| Penstemon veronicifolius Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon versicolor Pennell | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon verticillatus M.Martens & Galeotti | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon violaceus (Brandegee) A. Nelson | Accepted |  | TRO |  | 
	
		| Penstemon virens Pennell ex Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon virgatus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon virgatus var. arizonicus (A. Gray) D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon virgatus subsp. pseudoputus Crosswh. | Synonym |  | TRO |  | 
	
		| Penstemon viscidulus Nees | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon vizcainensis Moran | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon vulcanellus Crosswh. | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon wardii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon washingtonensis D.D. Keck | Accepted |  | TRO |  | 
	
		| Penstemon washoensis Greene | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon watsonii A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon wendtiorum B.L.Turner | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon wherryi Pennell | Accepted |  | TRO |  | 
	
		| Penstemon whippleanus A. Gray | Accepted |  | TRO |  | 
	
		| Penstemon whitedii Piper | Synonym |  | TRO |  | 
	
		| Penstemon whitedii subsp. dayanus (Howell) D.D. Keck | Unresolved |  | TRO |  | 
	
		| Penstemon wilcoxii Rydb. | Accepted |  | TRO |  | 
	
		| Penstemon wisconsinensis Pennell | Synonym |  | TRO |  | 
	
		| Penstemon wislizeni (A. Gray) Straw | Accepted |  | TRO |  | 
	
		| Penstemon woodsii A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon wrightii Hook. | Accepted |  | TRO |  | 
	
		| Penstemon xylus A.Nelson | Unresolved |  | WCSP (in review) |  | 
	
		| Penstemon yampaensis Penland | Accepted |  | TRO |  |