| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| PECA9 | Penstemon carnosus Pennell | fleshy beardtongue | Scrophulariaceae
|
| PECA17 | Penstemon caryi Pennell | Cary's beardtongue | Scrophulariaceae
|
| PECA20 | Penstemon caudatus Heller | Penstemon angustifolius var. caudatus | Scrophulariaceae
|
| PECE2 | Penstemon centranthifolius Benth. | scarlet bugler | Scrophulariaceae
|
| PECI10 | Penstemon cinerascens Greene ex C.F. Baker | Penstemon roezlii | Scrophulariaceae
|
| PECIF | Penstemon cinereus Piper var. foliatus Keck | Penstemon humilis ssp. humilis | Scrophulariaceae
|
| PECI11 | Penstemon cinereus Piper | Penstemon humilis ssp. humilis | Scrophulariaceae
|
| PECI2 | Penstemon cinicola Keck | ash penstemon | Scrophulariaceae
|
| PECL4 | Penstemon cleburnei M.E. Jones | Penstemon eriantherus var. cleburnei | Scrophulariaceae
|
| PECLC5 | Penstemon clevelandii Gray ssp. clevelandii | Cleveland's beardtongue | Scrophulariaceae
|
| PECLC4 | Penstemon clevelandii Gray ssp. connatus (Munz & Johnston) Keck | San Jacinto beardtongue | Scrophulariaceae
|
| PECLM2 | Penstemon clevelandii Gray ssp. mohavensis Keck | Cleveland's beardtongue | Scrophulariaceae
|
| PECLC6 | Penstemon clevelandii Gray var. connatus Munz & Johnston | Penstemon clevelandii ssp. connatus | Scrophulariaceae
|
| PECLM3 | Penstemon clevelandii Gray var. mohavensis (Keck) McMinn | Penstemon clevelandii ssp. mohavensis | Scrophulariaceae
|
| PECL | Penstemon clevelandii Gray | Cleveland's beardtongue | Scrophulariaceae
|
| PECL5 | Penstemon clutei A. Nels. | Sunset Crater beardtongue | Scrophulariaceae
|
| PECOP3 | Penstemon cobaea Nutt. ssp. purpureus (Pennell) Pennell | Penstemon cobaea | Scrophulariaceae
|
| PECOT | Penstemon cobaea Nutt. ssp. typicus Pennell | Penstemon cobaea | Scrophulariaceae
|
| PECOP2 | Penstemon cobaea Nutt. var. purpureus Pennell | Penstemon cobaea | Scrophulariaceae
|
| PECO4 | Penstemon cobaea Nutt. | cobaea beardtongue | Scrophulariaceae
|
| PECO26 | Penstemon coloradoensis A. Nels. | Penstemon linarioides ssp. coloradoensis | Scrophulariaceae
|
| PECO5 | Penstemon comarrhenus Gray | dusty beardtongue | Scrophulariaceae
|
| PECO10 | Penstemon compactus (Keck) Crosswhite | compact penstemon | Scrophulariaceae
|
| PECO15 | Penstemon concinnus Keck | Tunnel Springs beardtongue | Scrophulariaceae
|
| PECOP6 | Penstemon confertus Dougl. ex Lindl. ssp. procerus (Dougl. ex Graham) D.V. Clark | Penstemon procerus var. procerus | Scrophulariaceae
|
| PECOP5 | Penstemon confertus Dougl. ex Lindl. var. procerus (Dougl. ex Graham) Coville | Penstemon procerus var. procerus | Scrophulariaceae
|
| PECO6 | Penstemon confertus Dougl. ex Lindl. | yellow penstemon | Scrophulariaceae
|
| PECOP4 | Penstemon confusus M.E. Jones ssp. patens (M.E. Jones) Keck | Penstemon patens | Scrophulariaceae
|
| PECO7 | Penstemon confusus M.E. Jones | Owens Valley beardtongue | Scrophulariaceae
|
| PECO27 | Penstemon congestus (M.E. Jones) Pennell | Penstemon pachyphyllus var. congestus | Scrophulariaceae
|
| PECO30 | Penstemon cordifolius Benth. | Keckiella cordifolia | Scrophulariaceae
|
| PECO25 | Penstemon corymbosus Benth. ex A. DC. | Keckiella corymbosa | Scrophulariaceae
|
| PECRA | Penstemon crandallii A. Nels. ssp. atratus Keck | Crandall's beardtongue | Scrophulariaceae
|
| PECRC | Penstemon crandallii A. Nels. ssp. crandallii | Crandall's beardtongue | Scrophulariaceae
|
| PECRG | Penstemon crandallii A. Nels. ssp. glabrescens (Pennell) Keck | Crandall's beardtongue | Scrophulariaceae
|
| PECRP | Penstemon crandallii A. Nels. ssp. procumbens (Greene) Keck | Crandall's beardtongue | Scrophulariaceae
|
| PECRT2 | Penstemon crandallii A. Nels. ssp. taosensis (Keck) Kartesz & Gandhi | Taos penstemon | Scrophulariaceae
|
| PECRA2 | Penstemon crandallii A. Nels. var. atratus (Keck) N. Holmgren | Penstemon crandallii ssp. atratus | Scrophulariaceae
|
| PECRT3 | Penstemon crandallii A. Nels. var. taosensis (Keck) Nisbet & R.C. Jackson | Penstemon crandallii ssp. taosensis | Scrophulariaceae
|
| PECR5 | Penstemon crandallii A. Nels. | Crandall's beardtongue | Scrophulariaceae
|
| PECR6 | Penstemon �crideri A. Nels. (pro sp.) | | Scrophulariaceae
|
| PECU | Penstemon cusickii Gray | Cusick's beardtongue | Scrophulariaceae
|
| PECYC | Penstemon cyananthus Hook. ssp. compactus Keck | Penstemon compactus | Scrophulariaceae
|
| PECYL | Penstemon cyananthus Hook. ssp. longiflorus Pennell | Penstemon longiflorus | Scrophulariaceae
|
| PECYS | Penstemon cyananthus Hook. ssp. subglaber (Gray) Pennell | Penstemon cyananthus var. subglaber | Scrophulariaceae
|
| PECYC3 | Penstemon cyananthus Hook. var. compactus (Keck) Neese | Penstemon compactus | Scrophulariaceae
|
| PECYC2 | Penstemon cyananthus Hook. var. cyananthus | Wasatch beardtongue | Scrophulariaceae
|
| PECYL2 | Penstemon cyananthus Hook. var. longiflorus (Pennell) Neese | Penstemon longiflorus | Scrophulariaceae
|
| PECYS2 | Penstemon cyananthus Hook. var. subglaber (Gray) N. Holmgren | Wasatch beardtongue | Scrophulariaceae
|
| PECY2 | Penstemon cyananthus Hook. | Wasatch beardtongue | Scrophulariaceae
|
| PECY3 | Penstemon cyaneus Pennell | blue penstemon | Scrophulariaceae
|
| PECY4 | Penstemon cyanocaulis Payson | bluestem beardtongue | Scrophulariaceae
|
| PECY6 | Penstemon cyathophorus Rydb. | sagebrush beardtongue | Scrophulariaceae
|
| PEDA | Penstemon dasyphyllus Gray | Cochise beardtongue | Scrophulariaceae
|
| PEDAM | Penstemon davidsonii Greene ssp. menziesii Keck | Penstemon davidsonii var. menziesii | Scrophulariaceae
|
| PEDAD | Penstemon davidsonii Greene var. davidsonii | Davidson's penstemon | Scrophulariaceae
|
| PEDAE | Penstemon davidsonii Greene var. ellipticus (Coult. & Fisher) Boivin | Penstemon ellipticus | Scrophulariaceae
|
| PEDAM2 | Penstemon davidsonii Greene var. menziesii (Keck) Cronq. | Menzies' penstemon | Scrophulariaceae
|
| PEDAP | Penstemon davidsonii Greene var. praeteritus Cronq. | timberline beardtongue | Scrophulariaceae
|
| PEDA2 | Penstemon davidsonii Greene | Davidson's penstemon | Scrophulariaceae
|
| PEDE10 | Penstemon deamii Pennell | Deam's beardtongue | Scrophulariaceae
|
| PEDE11 | Penstemon deaveri Crosswhite | Mt. Graham beardtongue | Scrophulariaceae
|
| PEDE22 | Penstemon debilis O'Kane & J. Anderson | Parachute beardtongue | Scrophulariaceae
|
| PEDE21 | Penstemon decurvus Pennell ex Crosswhite | Penstemon humilis ssp. humilis | Scrophulariaceae
|
| PEDE12 | Penstemon degeneri Crosswhite | Degener's beardtongue | Scrophulariaceae
|
| PEDEH | Penstemon deustus Dougl. ex Lindl. ssp. heterander (Torr. & Gray) Pennell & Keck | Penstemon deustus var. pedicellatus | Scrophulariaceae
|
| PEDES | Penstemon deustus Dougl. ex Lindl. ssp. sudans (M.E. Jones) Pennell & Keck | Penstemon sudans | Scrophulariaceae
|
| PEDEV | Penstemon deustus Dougl. ex Lindl. ssp. variabilis (Suksdorf) Pennell & Keck | Penstemon deustus var. variabilis | Scrophulariaceae
|
| PEDED2 | Penstemon deustus Dougl. ex Lindl. var. deustus | scabland penstemon | Scrophulariaceae
|
| PEDEH2 | Penstemon deustus Dougl. ex Lindl. var. heterander (Torr. & Gray) Cronq. | Penstemon deustus var. pedicellatus | Scrophulariaceae
|
| PEDEP | Penstemon deustus Dougl. ex Lindl. var. pedicellatus M.E. Jones | scabland penstemon | Scrophulariaceae
|
| PEDES2 | Penstemon deustus Dougl. ex Lindl. var. suffrutescens L. Henderson | scabland penstemon | Scrophulariaceae
|
| PEDEV2 | Penstemon deustus Dougl. ex Lindl. var. variabilis (Suksdorf) Cronq. | scabland penstemon | Scrophulariaceae
|
| PEDE4 | Penstemon deustus Dougl. ex Lindl. | scabland penstemon | Scrophulariaceae
|
| PEDI | Penstemon digitalis Nutt. ex Sims | talus slope penstemon | Scrophulariaceae
|
| PEDI5 | Penstemon diphyllus Rydb. | twoleaf beardtongue | Scrophulariaceae
|
| PEDI6 | Penstemon discolor Keck | Cataiina beardtongue | Scrophulariaceae
|
| PEDI7 | Penstemon dissectus Ell. | dissected beardtongue | Scrophulariaceae
|
| PEDI10 | Penstemon distans N. Holmgren | Mt. Tumbull beardtongue | Scrophulariaceae
|
| PEDOD2 | Penstemon dolius M.E. Jones ex Pennell var. dolius | Jones' beardtongue | Scrophulariaceae
|
| PEDOD | Penstemon dolius M.E. Jones ex Pennell var. duchesnensis N. Holmgren | Duchesne penstemon | Scrophulariaceae
|
| PEDO3 | Penstemon dolius M.E. Jones ex Pennell | Jones' beardtongue | Scrophulariaceae
|
| PEDU5 | Penstemon �dubius A. Davids. (pro sp.) | | Scrophulariaceae
|
| PEDU4 | Penstemon duchesnensis (N. Holmgren) Neese | Penstemon dolius var. duchesnensis | Scrophulariaceae
|
| PEEAE2 | Penstemon eatonii Gray ssp. eatonii | Eaton's penstemon | Scrophulariaceae
|
| PEEAE | Penstemon eatonii Gray ssp. exsertus (A. Nels.) Keck | Eaton's penstemon | Scrophulariaceae
|
| PEEAU | Penstemon eatonii Gray ssp. undosus (M.E. Jones) Keck | Eaton's penstemon | Scrophulariaceae
|
| PEEAU2 | Penstemon eatonii Gray var. undosus M.E. Jones | Penstemon eatonii ssp. undosus | Scrophulariaceae
|
| PEEA | Penstemon eatonii Gray | Eaton's penstemon | Scrophulariaceae
|
| PEEL4 | Penstemon elegantulus Pennell | rockvine penstemon | Scrophulariaceae
|
| PEEL5 | Penstemon ellipticus Coult. & Fisher | rocky ledge penstemon | Scrophulariaceae
|
| PEERA | Penstemon eriantherus Pursh var. argillosus M.E. Jones | fuzzytongue penstemon | Scrophulariaceae
|
| PEERC | Penstemon eriantherus Pursh var. cleburnei (M.E. Jones) Dorn | Cleburn's penstemon | Scrophulariaceae
|
| PEERE | Penstemon eriantherus Pursh var. eriantherus | fuzzytongue penstemon | Scrophulariaceae
|
| PEERR | Penstemon eriantherus Pursh var. redactus Pennell & Keck | longsac penstemon | Scrophulariaceae
|
| PEERW | Penstemon eriantherus Pursh var. whitedii (Piper) A. Nels. | Whited's penstemon | Scrophulariaceae
|
| PEER | Penstemon eriantherus Pursh | fuzzytongue penstemon | Scrophulariaceae
|
| PEEU | Penstemon euglaucus English | glaucous beardtongue | Scrophulariaceae
|
| PEFE | Penstemon fendleri Torr. & Gray | Fendler's penstemon | Scrophulariaceae
|
| PEFI2 | Penstemon filiformis (Keck) Keck | threadleaf beardtongue | Scrophulariaceae
|
| PEFL6 | Penstemon flavescens Pennell | high mountain penstemon | Scrophulariaceae
|