| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| PEFLA | Penstemon floridus Brandeg. ssp. austinii (Eastw.) Keck | Penstemon floridus var. austinii | Scrophulariaceae
|
| PEFLA2 | Penstemon floridus Brandeg. var. austinii (Eastw.) N. Holmgren | Austin's beardtongue | Scrophulariaceae
|
| PEFLF | Penstemon floridus Brandeg. var. floridus | Panamint beardtongue | Scrophulariaceae
|
| PEFL3 | Penstemon floridus Brandeg. | Panamint beardtongue | Scrophulariaceae
|
| PEFL8 | Penstemon flowersii Neese & Welsh | Flowers' beardtongue | Scrophulariaceae
|
| PEFR7 | Penstemon francisci-pennellii Crosswhite | Penstemon leiophyllus var. francisci-pennellii | Scrophulariaceae
|
| PEFR9 | Penstemon franklinii Welsh | Franklin's penstemon | Scrophulariaceae
|
| PEFRF5 | Penstemon fremontii Torr. & Gray ex Gray var. fremontii | Fremont's beardtongue | Scrophulariaceae
|
| PEFRG | Penstemon fremontii Torr. & Gray ex Gray var. glabrescens Dorn & Lichvar | Fremont's beardtongue | Scrophulariaceae
|
| PEFR | Penstemon fremontii Torr. & Gray ex Gray | Fremont's beardtongue | Scrophulariaceae
|
| PEFRA | Penstemon fruticiformis Coville ssp. amargosae Keck | Death Valley beardtongue | Scrophulariaceae
|
| PEFRF3 | Penstemon fruticiformis Coville ssp. fruticiformis | Death Valley beardtongue | Scrophulariaceae
|
| PEFRA4 | Penstemon fruticiformis Coville var. amargosae (Keck) N. Holmgren | Penstemon fruticiformis ssp. amargosae | Scrophulariaceae
|
| PEFR2 | Penstemon fruticiformis Coville | Death Valley beardtongue | Scrophulariaceae
|
| PEFRS3 | Penstemon fruticosus (Pursh) Greene ssp. scouleri (Lindl.) Pennell & Keck | Penstemon fruticosus var. scouleri | Scrophulariaceae
|
| PEFRS4 | Penstemon fruticosus (Pursh) Greene ssp. serratus Keck | Penstemon fruticosus var. serratus | Scrophulariaceae
|
| PEFRF4 | Penstemon fruticosus (Pursh) Greene var. fruticosus | bush penstemon | Scrophulariaceae
|
| PEFRS | Penstemon fruticosus (Pursh) Greene var. scouleri (Lindl.) Cronq. | littleleaf bush penstemon | Scrophulariaceae
|
| PEFRS2 | Penstemon fruticosus (Pursh) Greene var. serratus (Keck) Cronq. | sawleaf bush penstemon | Scrophulariaceae
|
| PEFR3 | Penstemon fruticosus (Pursh) Greene | bush penstemon | Scrophulariaceae
|
| PEGAH | Penstemon gairdneri Hook. ssp. hians (Piper) Keck | Penstemon gairdneri var. gairdneri | Scrophulariaceae
|
| PEGAO | Penstemon gairdneri Hook. ssp. oreganus (Gray) Keck | Penstemon gairdneri var. oreganus | Scrophulariaceae
|
| PEGAG2 | Penstemon gairdneri Hook. var. gairdneri | Gairdner's beardtongue | Scrophulariaceae
|
| PEGAH2 | Penstemon gairdneri Hook. var. hians Piper | Penstemon gairdneri var. gairdneri | Scrophulariaceae
|
| PEGAO2 | Penstemon gairdneri Hook. var. oreganus Gray | Gairdner's beardtongue | Scrophulariaceae
|
| PEGA | Penstemon gairdneri Hook. | Gairdner's beardtongue | Scrophulariaceae
|
| PEGA4 | Penstemon garrettii Pennell | Penstemon scariosus var. garrettii | Scrophulariaceae
|
| PEGE3 | Penstemon gentianoides (Kunth) Poir. | gentian beardtongue | Scrophulariaceae
|
| PEGI4 | Penstemon gibbensii Dorn | Gibbens' beardtongue | Scrophulariaceae
|
| PEGLA | Penstemon glaber Pursh var. alpinus (Torr.) Gray | alpine sawsepal penstemon | Scrophulariaceae
|
| PEGLB | Penstemon glaber Pursh var. brandegeei (Porter) Freeman | Brandegee's penstemon | Scrophulariaceae
|
| PEGLG2 | Penstemon glaber Pursh var. glaber | sawsepal penstemon | Scrophulariaceae
|
| PEGL3 | Penstemon glaber Pursh | sawsepal penstemon | Scrophulariaceae
|
| PEGLC | Penstemon glandulosus Dougl. ssp. chelanensis Keck | Penstemon glandulosus var. chelanensis | Scrophulariaceae
|
| PEGLC2 | Penstemon glandulosus Dougl. var. chelanensis (Keck) Cronq. | stickystem penstemon | Scrophulariaceae
|
| PEGLG3 | Penstemon glandulosus Dougl. var. glandulosus | stickystem penstemon | Scrophulariaceae
|
| PEGL4 | Penstemon glandulosus Dougl. | stickystem penstemon | Scrophulariaceae
|
| PEGL10 | Penstemon glaucinus Pennell | blueleaf beardtongue | Scrophulariaceae
|
| PEGL5 | Penstemon globosus (Piper) Pennell & Keck | globe penstemon | Scrophulariaceae
|
| PEGO2 | Penstemon goodrichii N. Holmgren | Lapoint beardtongue | Scrophulariaceae
|
| PEGO | Penstemon gormanii Greene | Gorman's beardtongue | Scrophulariaceae
|
| PEGR4 | Penstemon gracilentus Gray | slender penstemon | Scrophulariaceae
|
| PEGRW | Penstemon gracilis Nutt. ssp. wisconsinensis (Pennell) Pennell | Penstemon gracilis var. wisconsinensis | Scrophulariaceae
|
| PEGRG3 | Penstemon gracilis Nutt. var. gracilis | lilac penstemon | Scrophulariaceae
|
| PEGRW2 | Penstemon gracilis Nutt. var. wisconsinensis (Pennell) Fassett | Wisconsin penstemon | Scrophulariaceae
|
| PEGR5 | Penstemon gracilis Nutt. | lilac penstemon | Scrophulariaceae
|
| PEGR6 | Penstemon grahamii Keck | Uinta Basin beardtongue | Scrophulariaceae
|
| PEGR7 | Penstemon grandiflorus Nutt. | large beardtongue | Scrophulariaceae
|
| PEGR20 | Penstemon griffinii A. Nels. | Griffin's beardtongue | Scrophulariaceae
|
| PEGRG4 | Penstemon grinnellii Eastw. ssp. grinnellii | Grinnell's beardtongue | Scrophulariaceae
|
| PEGRS | Penstemon grinnellii Eastw. ssp. scrophularioides (M.E. Jones) Munz | Grinnell's beardtongue | Scrophulariaceae
|
| PEGRS4 | Penstemon grinnellii Eastw. var. scrophularioides (M.E. Jones) N. Holmgren | Penstemon grinnellii ssp. scrophularioides | Scrophulariaceae
|
| PEGR8 | Penstemon grinnellii Eastw. | Grinnell's beardtongue | Scrophulariaceae
|
| PEGUE | Penstemon guadalupensis Heller var. ernstii (Pennell) Cory | Penstemon guadalupensis | Scrophulariaceae
|
| PEGU | Penstemon guadalupensis Heller | Guadalupe beardtongue | Scrophulariaceae
|
| PEHA9 | Penstemon hallii Gray | Hall's beardtongue | Scrophulariaceae
|
| PEHA10 | Penstemon harbourii Gray | Harbour's beardtongue | Scrophulariaceae
|
| PEHA11 | Penstemon harringtonii Penl. | Harrington's beardtongue | Scrophulariaceae
|
| PEHA18 | Penstemon hartwegii Benth. | Hartweg's beardtongue | Scrophulariaceae
|
| PEHA2 | Penstemon havardii Gray | Big Bend beardtongue | Scrophulariaceae
|
| PEHA12 | Penstemon haydenii S. Wats. | blowout beardtongue | Scrophulariaceae
|
| PEHE10 | Penstemon helleri Small | Penstemon triflorus ssp. integrifolius | Scrophulariaceae
|
| PEHE9 | Penstemon hesperius M.E. Peck | Penstemon rydbergii var. rydbergii | Scrophulariaceae
|
| PEHEC | Penstemon heterodoxus Gray ssp. cephalophorus (Greene) Keck | Penstemon heterodoxus var. cephalophorus | Scrophulariaceae
|
| PEHEC2 | Penstemon heterodoxus Gray var. cephalophorus (Greene) N. Holmgren | Sierra beardtongue | Scrophulariaceae
|
| PEHEH3 | Penstemon heterodoxus Gray var. heterodoxus | Sierra beardtongue | Scrophulariaceae
|
| PEHES2 | Penstemon heterodoxus Gray var. shastensis (Keck) N. Holmgren | Shasta beardtongue | Scrophulariaceae
|
| PEHE2 | Penstemon heterodoxus Gray | Sierra beardtongue | Scrophulariaceae
|
| PEHEA | Penstemon heterophyllus Lindl. ssp. australis (Munz & Johnston) Keck | foothill beardtongue | Scrophulariaceae
|
| PEHEH2 | Penstemon heterophyllus Lindl. ssp. heterophyllus | bunchleaf penstemon | Scrophulariaceae
|
| PEHEP | Penstemon heterophyllus Lindl. ssp. purdyi Keck | Purdy's penstemon | Scrophulariaceae
|
| PEHEA2 | Penstemon heterophyllus Lindl. var. australis Munz & Johnston | Penstemon heterophyllus ssp. australis | Scrophulariaceae
|
| PEHEP3 | Penstemon heterophyllus Lindl. var. purdyi (Keck) McMinn | Penstemon heterophyllus ssp. purdyi | Scrophulariaceae
|
| PEHE3 | Penstemon heterophyllus Lindl. | bunchleaf penstemon | Scrophulariaceae
|
| PEHIM | Penstemon hirsutus (L.) Willd. var. minimus Bennett | Penstemon hirsutus | Scrophulariaceae
|
| PEHIP | Penstemon hirsutus (L.) Willd. var. pygmaeus Bennett | Penstemon hirsutus | Scrophulariaceae
|
| PEHI | Penstemon hirsutus (L.) Willd. | hairy beardtongue | Scrophulariaceae
|
| PEHO8 | Penstemon holmgrenii S. Clark | Penstemon cyananthus var. subglaber | Scrophulariaceae
|
| PEHUB | Penstemon humilis Nutt. ex Gray ssp. brevifolius (Gray) Keck | low beardtongue | Scrophulariaceae
|
| PEHUH | Penstemon humilis Nutt. ex Gray ssp. humilis | low beardtongue | Scrophulariaceae
|
| PEHUO | Penstemon humilis Nutt. ex Gray ssp. obtusifolius (Pennell) Keck | low beardtongue | Scrophulariaceae
|
| PEHUB2 | Penstemon humilis Nutt. ex Gray var. brevifolius Gray | Penstemon humilis ssp. brevifolius | Scrophulariaceae
|
| PEHUD | Penstemon humilis Nutt. ex Gray var. ?deserticus Welsh | Penstemon humilis ssp. humilis | Scrophulariaceae
|
| PEHUO2 | Penstemon humilis Nutt. ex Gray var. obtusifolius (Pennell) Reveal | Penstemon humilis ssp. obtusifolius | Scrophulariaceae
|
| PEHU | Penstemon humilis Nutt. ex Gray | low beardtongue | Scrophulariaceae
|
| PEID | Penstemon idahoensis Atwood & Welsh | Idaho beardtongue | Scrophulariaceae
|
| PEIM2 | Penstemon immanifestus N. Holmgren | Steptoe Valley beardtongue | Scrophulariaceae
|
| PEIN3 | Penstemon incertus Brandeg. | Mojave beardtongue | Scrophulariaceae
|
| PEIN9 | Penstemon inflatus Crosswhite | inflated beardtongue | Scrophulariaceae
|
| PEJAB | Penstemon jamesii Benth. ssp. breviculus Keck | Penstemon breviculus | Scrophulariaceae
|
| PEJAO | Penstemon jamesii Benth. ssp. ophianthus (Pennell) Keck | Penstemon ophianthus | Scrophulariaceae
|
| PEJAT | Penstemon jamesii Benth. ssp. typicus Keck | Penstemon jamesii | Scrophulariaceae
|
| PEJA | Penstemon jamesii Benth. | James' beardtongue | Scrophulariaceae
|
| PEJA2 | Penstemon janishiae N. Holmgren | Antelope Valley beardtongue | Scrophulariaceae
|
| PEJO2 | Penstemon �jonesii Pennell (pro sp.) | | Scrophulariaceae
|
| PEKE2 | Penstemon keckii Clokey | Penstemon leiophyllus var. keckii | Scrophulariaceae
|
| PEKI | Penstemon kingii S. Wats. | King's beardtongue | Scrophulariaceae
|
| PELA6 | Penstemon labrosus (Gray) Hook. f. | San Gabriel beardtongue | Scrophulariaceae
|
| PELAL6 | Penstemon laetus Gray ssp. laetus | mountain blue penstemon | Scrophulariaceae
|
| PELAL | Penstemon laetus Gray ssp. leptosepalus (Greene ex Gray) Keck | mountain blue penstemon | Scrophulariaceae
|
| PELAR3 | Penstemon laetus Gray ssp. roezlii (Regel) Keck | Penstemon roezlii | Scrophulariaceae
|