| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| PELAL10 | Penstemon laetus Gray var. leptosepalus Greene ex Gray | Penstemon laetus ssp. leptosepalus | Scrophulariaceae
|
| PELAR4 | Penstemon laetus Gray var. roezlii (Regel) Jepson | Penstemon roezlii | Scrophulariaceae
|
| PELAS3 | Penstemon laetus Gray var. sagittatus (Keck) McMinn | Penstemon laetus ssp. sagittatus | Scrophulariaceae
|
| PELA7 | Penstemon laetus Gray | mountain blue penstemon | Scrophulariaceae
|
| PELAA4 | Penstemon laevigatus Ait. ssp. alluviorum (Pennell) Bennett | Penstemon alluviorum | Scrophulariaceae
|
| PELAC | Penstemon laevigatus Ait. ssp. calycosus (Small) Bennett | Penstemon calycosus | Scrophulariaceae
|
| PELAD2 | Penstemon laevigatus Ait. ssp. digitalis (Nutt. ex Sims) Bennett | Penstemon digitalis | Scrophulariaceae
|
| PELAA5 | Penstemon laevigatus Ait. var. angulatus Bennett | Penstemon digitalis | Scrophulariaceae
|
| PELAD3 | Penstemon laevigatus Ait. var. deamii (Pennell) Bennett | Penstemon deamii | Scrophulariaceae
|
| PELA8 | Penstemon laevigatus Ait. | eastern smooth beardtongue | Scrophulariaceae
|
| PELA15 | Penstemon laevis Pennell | southwestern beardtongue | Scrophulariaceae
|
| PELA16 | Penstemon lanceolatus auct. non Benth. | Penstemon ramosus | Scrophulariaceae
|
| PELAE | Penstemon laricifolius Hook. & Arn. ssp. exilifolius (A. Nels.) Keck | larchleaf beardtongue | Scrophulariaceae
|
| PELAL7 | Penstemon laricifolius Hook. & Arn. ssp. laricifolius | larchleaf beardtongue | Scrophulariaceae
|
| PELAE2 | Penstemon laricifolius Hook. & Arn. var. exilifolius (A. Nels.) Payson | Penstemon laricifolius ssp. exilifolius | Scrophulariaceae
|
| PELA9 | Penstemon laricifolius Hook. & Arn. | larchleaf beardtongue | Scrophulariaceae
|
| PELA10 | Penstemon laxiflorus Pennell | nodding beardtongue | Scrophulariaceae
|
| PELA17 | Penstemon laxus A. Nels. | tufted penstemon | Scrophulariaceae
|
| PELEF | Penstemon leiophyllus Pennell var. francisci-pennellii (Crosswhite) N. Holmgren | smoothleaf beardtongue | Scrophulariaceae
|
| PELEK | Penstemon leiophyllus Pennell var. keckii (Clokey) N. Holmgren | Keck's beardtongue | Scrophulariaceae
|
| PELEL | Penstemon leiophyllus Pennell var. leiophyllus | smoothleaf beardtongue | Scrophulariaceae
|
| PELE7 | Penstemon leiophyllus Pennell | smoothleaf beardtongue | Scrophulariaceae
|
| PELE8 | Penstemon lemhiensis (Keck) Keck & Cronq. | Lemhi penstemon | Scrophulariaceae
|
| PELE13 | Penstemon lemmonii Gray | Keckiella lemmonii | Scrophulariaceae
|
| PELEA2 | Penstemon lentus Pennell ssp. albiflorus Keck | Penstemon lentus var. albiflorus | Scrophulariaceae
|
| PELEA3 | Penstemon lentus Pennell var. albiflorus (Keck) Reveal | handsome beardtongue | Scrophulariaceae
|
| PELEL2 | Penstemon lentus Pennell var. lentus | handsome beardtongue | Scrophulariaceae
|
| PELE2 | Penstemon lentus Pennell | handsome beardtongue | Scrophulariaceae
|
| PELEH | Penstemon leonardii Rydb. var. higginsii Neese | Higgins' beardtongue | Scrophulariaceae
|
| PELEL3 | Penstemon leonardii Rydb. var. leonardii | Leonard's beardtongue | Scrophulariaceae
|
| PELEP | Penstemon leonardii Rydb. var. patricus (N. Holmgren) Neese | Leonard's beardtongue | Scrophulariaceae
|
| PELE9 | Penstemon leonardii Rydb. | Leonard's beardtongue | Scrophulariaceae
|
| PELE14 | Penstemon leptanthus Pennell | Sevier Plateau beardtongue | Scrophulariaceae
|
| PELIC | Penstemon linarioides Gray ssp. coloradoensis (A. Nels.) Keck | toadflax penstemon | Scrophulariaceae
|
| PELIC2 | Penstemon linarioides Gray ssp. compactifolius Keck | toadflax beardtongue | Scrophulariaceae
|
| PELIL2 | Penstemon linarioides Gray ssp. linarioides | toadflax beardtongue | Scrophulariaceae
|
| PELIM | Penstemon linarioides Gray ssp. maguirei Keck | Maguire's penstemon | Scrophulariaceae
|
| PELIS | Penstemon linarioides Gray ssp. sileri (Gray) Keck | Siler's penstemon | Scrophulariaceae
|
| PELIT2 | Penstemon linarioides Gray ssp. taosensis Keck | Penstemon crandallii ssp. taosensis | Scrophulariaceae
|
| PELIT | Penstemon linarioides Gray ssp. typicus Keck | Penstemon linarioides ssp. linarioides | Scrophulariaceae
|
| PELIS2 | Penstemon linarioides Gray var. sileri Gray | Penstemon linarioides ssp. sileri | Scrophulariaceae
|
| PELIV | Penstemon linarioides Gray var. viridis Keck | Penstemon linarioides ssp. sileri | Scrophulariaceae
|
| PELI2 | Penstemon linarioides Gray | toadflax penstemon | Scrophulariaceae
|
| PELO5 | Penstemon longiflorus (Pennell) S.L. Clark | longflower penstemon | Scrophulariaceae
|
| PELY2 | Penstemon lyallii (Gray) Gray | Lyall's beardtongue | Scrophulariaceae
|
| PEMA16 | Penstemon macranthus Eastw. | Penstemon palmeri var. macranthus | Scrophulariaceae
|
| PEMA15 | Penstemon maguirei Crosswhite | Penstemon arenarius | Scrophulariaceae
|
| PEMA13 | Penstemon marcusii (Keck) N. Holmgren | Marcus' beardtongue | Scrophulariaceae
|
| PEME2 | Penstemon mensarum Pennell | tiger beardtongue | Scrophulariaceae
|
| PEMED | Penstemon menziesii Hook. ssp. davidsonii (Greene) Piper | Penstemon davidsonii var. davidsonii | Scrophulariaceae
|
| PEMET | Penstemon menziesii Hook. ssp. thompsonii Pennell | Penstemon davidsonii var. davidsonii | Scrophulariaceae
|
| PEME12 | Penstemon menziesii Hook. p.p. | Penstemon davidsonii var. menziesii | Scrophulariaceae
|
| PEMI12 | Penstemon microphyllus Gray | Keckiella antirrhinoides ssp. microphylla | Scrophulariaceae
|
| PEMI13 | Penstemon minidokanus A. Nels. & J.F. Macbr. | Penstemon perpulcher | Scrophulariaceae
|
| PEMI8 | Penstemon �mirus A. Nels. (pro sp.) | | Scrophulariaceae
|
| PEMI3 | Penstemon miser Gray | Malheur penstemon | Scrophulariaceae
|
| PEMO11 | Penstemon modestus Greene | Penstemon procerus var. modestus | Scrophulariaceae
|
| PEMOM3 | Penstemon moffatii Eastw. ssp. marcusii Keck | Penstemon marcusii | Scrophulariaceae
|
| PEMOM | Penstemon moffatii Eastw. ssp. moffatii | Moffatt's beardtongue | Scrophulariaceae
|
| PEMOP | Penstemon moffatii Eastw. ssp. paysonii (Pennell) Keck | Moffatt's beardtongue | Scrophulariaceae
|
| PEMO3 | Penstemon moffatii Eastw. | Moffatt's beardtongue | Scrophulariaceae
|
| PEMO | Penstemon monoensis Heller | Mono penstemon | Scrophulariaceae
|
| PEMOI | Penstemon montanus Greene ssp. idahoensis Pennell & Keck | Penstemon montanus var. idahoensis | Scrophulariaceae
|
| PEMOI2 | Penstemon montanus Greene var. idahoensis (Pennell & Keck) Cronq. | Central Idaho penstemon | Scrophulariaceae
|
| PEMOM2 | Penstemon montanus Greene var. montanus | cordroot beardtongue | Scrophulariaceae
|
| PEMO4 | Penstemon montanus Greene | cordroot beardtongue | Scrophulariaceae
|
| PEMO5 | Penstemon moriahensis N. Holmgren | Mt. Moriah beardtongue | Scrophulariaceae
|
| PEMU7 | Penstemon mucronatus N. Holmgren | Penstemon pachyphyllus var. mucronatus | Scrophulariaceae
|
| PEMU8 | Penstemon multicaulis Pennell | Penstemon arkansanus | Scrophulariaceae
|
| PEMU9 | Penstemon multiflorus Chapman ex Benth. | manyflower beardtongue | Scrophulariaceae
|
| PEMU2 | Penstemon murrayanus Hook. | scarlet beardtongue | Scrophulariaceae
|
| PENA3 | Penstemon nanus Keck | dwarf beardtongue | Scrophulariaceae
|
| PENA4 | Penstemon navajoa N. Holmgren | Navajo Mountain beardtongue | Scrophulariaceae
|
| PENE8 | Penstemon nemorosus (Dougl. ex Lindl.) Trautv. | Nothochelone nemorosa | Scrophulariaceae
|
| PENE6 | Penstemon neomexicanus Woot. & Standl. | New Mexico beardtongue | Scrophulariaceae
|
| PENE2 | Penstemon neotericus Keck | Plumas County beardtongue | Scrophulariaceae
|
| PENEB | Penstemon newberryi Gray ssp. berryi (Eastw.) Keck | Berry's penstemon | Scrophulariaceae
|
| PENEN | Penstemon newberryi Gray ssp. newberryi | mountain pride | Scrophulariaceae
|
| PENES | Penstemon newberryi Gray ssp. sonomensis (Greene) Keck | Sonoma penstemon | Scrophulariaceae
|
| PENEB3 | Penstemon newberryi Gray var. berryi (Eastw.) N. Holmgren | Penstemon newberryi ssp. berryi | Scrophulariaceae
|
| PENES3 | Penstemon newberryi Gray var. sonomensis (Greene) Jepson | Penstemon newberryi ssp. sonomensis | Scrophulariaceae
|
| PENE3 | Penstemon newberryi Gray | mountain pride | Scrophulariaceae
|
| PENIP | Penstemon nitidus Dougl. ex Benth. ssp. polyphyllus Pennell | Penstemon nitidus var. polyphyllus | Scrophulariaceae
|
| PENIN | Penstemon nitidus Dougl. ex Benth. var. nitidus | waxleaf penstemon | Scrophulariaceae
|
| PENIP2 | Penstemon nitidus Dougl. ex Benth. var. polyphyllus (Pennell) Cronq. | waxleaf penstemon | Scrophulariaceae
|
| PENI3 | Penstemon nitidus Dougl. ex Benth. | waxleaf penstemon | Scrophulariaceae
|
| PENU | Penstemon nudiflorus Gray | Flagstaff beardtongue | Scrophulariaceae
|
| PENY | Penstemon nyeensis Crosswhite | Penstemon kingii | Scrophulariaceae
|
| PEOK | Penstemon oklahomensis Pennell | Oklahoma beardtongue | Scrophulariaceae
|
| PEOL | Penstemon oliganthus Woot. & Standl. | Apache beardtongue | Scrophulariaceae
|
| PEOP | Penstemon ophianthus Pennell | coiled anther penstemon | Scrophulariaceae
|
| PEOR3 | Penstemon oreocharis Greene | Penstemon rydbergii var. oreocharis | Scrophulariaceae
|
| PEOS | Penstemon osterhoutii Pennell | Osterhout's beardtongue | Scrophulariaceae
|
| PEOVP | Penstemon ovatus Dougl. ex Hook. var. pinetorum Piper | Penstemon wilcoxii | Scrophulariaceae
|
| PEOV2 | Penstemon ovatus Dougl. ex Hook. | eggleaf beardtongue | Scrophulariaceae
|
| PEPAC | Penstemon pachyphyllus Gray ex Rydb. ssp. congestus (M.E. Jones) Keck | Penstemon pachyphyllus var. congestus | Scrophulariaceae
|
| PEPAC2 | Penstemon pachyphyllus Gray ex Rydb. var. congestus (M.E. Jones) N. Holmgren | thickleaf beardtongue | Scrophulariaceae
|
| PEPAM5 | Penstemon pachyphyllus Gray ex Rydb. var. mucronatus (N. Holmgren) Neese | mucronate penstemon | Scrophulariaceae
|
| PEPAP8 | Penstemon pachyphyllus Gray ex Rydb. var. pachyphyllus | thickleaf beardtongue | Scrophulariaceae
|
| PEPA6 | Penstemon pachyphyllus Gray ex Rydb. | thickleaf beardtongue | Scrophulariaceae
|
| PEPA23 | Penstemon pahutensis N. Holmgren | Paiute beardtongue | Scrophulariaceae
|