Species in or near New Mexico
alamosensis albidus ambiguus angustifolius auriberbis
barbatus breviculus buckleyi campanulatus cardinalis
cobaea comarrhenus crandallii dasyphyllus deaveri
eatonii fendleri glaber gracilis grandiflorus
griffinii inflatus jamesii lanceolatus lentus
linarioides metcalfei neomexicanus oliganthus ophianthus
palmeri parviflorus pinifolius procerus pseudoparvus
pseudospectabilis rostiflorus rydbergii secundiflorus strictiformis
strictus superbus thurberi virgatus whippleanus

Originally prepared by: David Bleakly, Albuquerque, NM
Presented in: The New Mexico Botanist (Number 9) August 3, 1998
Reprinted with permission of: American Penstemon Society,

Step Description Next Step or Species
1 Plants shrubby; leaves linear & < 35 mm long >2
1 Plants herbaceous or woody only at the base; leaves linear or broader >4
2 Corolla blue, blue-purple, or reddish purple; 8-14 mm long, all lobes spreading; tube gradually expanded; desert grasslands in sNM (CA, HI, LU), sAZ, sCA, nMEX; Apr-Aug P thurberi
2 Corolla pink externally, 15 24 mm long, white on the face of the lobes; upper lobes reflexed, lower lobes projecting; tube narrow and curved >3
3 Stems puberulous; sandy soils in eNM (BE, CU, DB, GU, LE, QU, RO, SF, TO, UN), eCO, wTX, wOK; (May) Jun-Jul (Aug) P ambiguus ambiguus
3 Stems glabrous; sNM (ED, LU, SO), AZ, TX, NV, MEX; Jun-Jul P ambiguus laevissimus
4 Leaves linear and short (< 35 mm long) >5
4 Leaves not linear or if linear, then much longer than 35 mm >10
5 Corollas red, 25-32 mm long, tubular, strongly bilabiate; inflorescence secund, glandular; anthers explanate, glabrous; staminode bearded most of length with bright yellow hairs; base of lower lobes with long, flat, yellow hairs; stems woody well above base; leaves small, needlelike, crowded on lower part of stems; rocky areas in swNM (CA, GR, ffl, SO), seAZ, nMEX; 5800-10,000 ft; Jun-Aug P pinifolius
5 Corollas some shade of blue or purplish; bottom of corolla throat plicate (2-ridged) forming a low palate >6
6 Stems and leaves puberulous with flat, appressed scale-like hairs, especially on lower leaves; leaves scattered on flowering stems; calyx lobes acute or very short acuminate, scarious margined almost to tip [linarioides subspecies] >7
6 Stems and leaves puberulous with fine erect or retrorse hairs, or leaves glabrous; leaves numerous on flowering stems; calyx lobes long acuminate, scarious margined only at base [crandalli subspecies] >9
7 Principal leaves mostly lanceolate to oblanceolate; limestone cliffs; apparently last collected in NM in 1880 (Gila valley, GR), seAZ P linariodes maguirei
7 Principal leaves essentially linear; base of lower lobes lightly bearded >8
8 Staminode sparsely bearded with short hairs, longer golden hairs in apical tuft; base of lower lobes lightly bearded; plants shorter (1-3.5 dm); resembles P. crandallii glabrescens in habit; vestiture variable; common in plains & foothills with sagebrush, PJ , oak in nwNM (CI, MC, RA, SJ) & swCO; 5200-8700 ft; Jun-Jul P linarioides coloradoensis
8 Staminode more densely bearded with longer hairs for most of its length; base of lower lobes strongly bearded; plants relatively tall (2-5 dm), scoparioid, stern bases more-or-less woody; common in canyons & foothills in PJ & PIPO in swNM (DA, CA, GR, HI, LU, MC, SI, SO) & seAZ; 4500-6000 ft; Jun Aug P linarioides linarioides
9 Leaves glabrous ventrally; dry hillsides in nwNM (CO, SA, RA, TA) & sCO; 6900-9000 ft; Jun-Aug P crandalli glabrescens
9 Leaves puberulous with fine erect or retrorse hairs; ncNM near Taos (RA, TA) P crandalli taosensis
10 Upper stem leaves connate perfoliate (upper stem leaves of P. superbus sometimes connate-perfoliate, but not serrate); corolla pink to rose, 25-35 mm; leaves usually serrate >11
10 Upper stem leaves sessile or subcordate; corollas various colors (rarely pink to rose or white); leaf margins various >12
11 Corolla expanding gradually, pale pink to rose; staminode glabrous; anthers explanate; plants glabrous, inflorescence glandular; rocky places in PJ/oak & PIPO in swNM (CA, DA, GR, HI), AZ, sNV, nMEX; 4500-7000 ft; Apr-Jun (Aug) P pseudospectabilis connatifolius
11 Corolla expanding abruptly; staminode bearded; anthers explanate or not; plants glaucous, inflorescence glandular; disjunct in NM, but now established in at least two places along 140; cNM (BE, TO), cAZ & westward; 5000-7000 ft (in NM); May-Jun (in NM) P palmeri palmeri
12 Corolla some shade of red but not pink to rose, usually tubular or slightly expanding >13
12 Corolla some shade of blue or purple (rarely white or pink) >22
13 Corolla constricted at orifice & with long yellow hairs; staminode bearded near tip; anthers minutely spinescent on sutures, opening all but the connective, & minutely puberulent >14
13 Corolla not constricted at orifice, with hairs or not; anthers glabrous or not, spinescent on sutures or not >15
14 Stem leaves moderately thin, broadly lanceolate, oblong, or lance-ovate, lower ones 10-20 cm long; calyx 3 mm long; rocky areas in PIPO & PSME in scNM only (LI, OT, SO - Capitan, Sacramento, & Oscura Mts); 6600-8800 ft; Jun Jul; RARE P cardinalis cardinalis
14 Stem leaves moderately thick, ovate or subcordate, lower ones 5 6 cm long; calyx 4-6 mm long; rocky areas in chaparral, PJ, & PIPO in seNM (ED, OT), tpTX (Guadalupe Mts of both states); 4500-5500 ft; May Jun; RARE P cardinalis regalis
15 Anther sacs dehiscent by a short slit across the connective, the tips remaining closed, U-shaped, sutures spinescent; corolla glandular, strongly bilabiate, upper lip projecting & forming galeate hood, glabrous within; staminode glabrous; sagebrush, PJ, oak, PIPO in wNM (CA), AZ, swCO, sUT, NV, sCA; 5200-9000 ft; (Jun) Jul-Aug (Oct) P rostriflorus
15 Anther sacs completely or partially dehiscent, the tips open >16
16 Anther sacs explanate >17
16 Anther sacs not explanate >18
17 Staminode glabrous; foliage not glaucous; corolla bright red; rocky areas in limestone, Sacramento Mts only (DA, OT); 4300-5300 ft; May-Jun; RARE P alamoensis
17 Staminode bearded; foliage strongly glaucous; corolla orange-pink to scarlet; PJ, oak, PIPO in rocky areas & washes in swNM (GR, ffl), seAZ, nMEX; 3500-5200 ft; Mar-Jim; RARE P superbus
18 Corolla bilabiate but not strongly so, lower lobes short, rounded, usually spreading; throat glabrous >19
18 Corolla strongly bilabiate, lower lobes long, narrow, reflexed, upper lobes projecting; throat usually bearded [barbatus subspecies] >20
19 Corolla barely bilabiate, almost regular; inflorescence glabrous or puberulent; anthers U-shaped, opening at tips only, minutely puberulent, sutures denticulate; staminode glabrous to slightly bearded at tip; dry slopes & flats in sagebrush, PJ, & PIPO in nwNM (SJ), swCO, UT, AZ; 5000-9200 ft; Apr-Jun (Jul) P eatonii undosus
19 Corolla strongly bilabiate, lower lobes long, narrow, reflexed, upper lobes projecting; throat usually bearded P lanceolatus
20 Base of lower lobes bearded with yellow hairs; calyx lobes 6-10 mm long; PJ, oak, & PIPO in swNM (CA, GR, HI, SI), seAZ, tpTX, nMEX; 5200-10,000 ft; Jun-Sep P barbatus barbatus
20 Base of lower lobes glabrous or bearded with a few white or yellowish hairs; calyx lobes < 6 mm long >21
21 Anthers bearded; dry hillsides in PJ, oak, PIPO in nwNM (CA, CI, MC, RA, SA, SJ, SO), swCO, seUT, neAZ; 5200-8200 ft; Jun-Aug P barbatus torreyi
21 Anthers bearded; dry hillsides in PJ, oak, PIPO in nwNM (CA, CI, MC, RA, SA, SJ, SO), swCO, seUT, neAZ; 5200-8200 ft; Jun-Aug P barbatus trichander
22 Foliage glabrous and slightly to heavily glaucous; leaves usually thickened or fleshy; staminode tip expanded >23
22 Foliage glabrous, puberulent, &/or glandular, but not glaucous; leaves not thickened; staminode tip expanded or not >29
23 Most of the inflorescence bracts prominent; inflorescence compact, not secund, the very short internodes, pedicels, and peduncles giving the effect of a spike of flowers >24
23 Only the lower inflorescence bracts prominent; inflorescences not spike-like, usually open, either n to distinctly secund or not; anthers completely dehiscent but not explanate, glabrous, sutures minutely spinescent >27
24 Bracts lance-ovate to orbicular, acute to short acuminate, large, conspecuous, often overlapping, clasping >25
24 Bracts lance-ovate or ovate, smaller, usually caudate; inflorescence congested; corolla sky-blue, violet-blue, or pinkish (often in same inflorescence); [these two subspecies of angustifolius may not be worthy of distinction since only flower color is different] >26
25 Plants tall (usually 5-10 dm); calyx lobes 7-13 mm long; flowers 35-48 mm long; inflorescence open; corolla pink, bluish lavender, or pale blue, abruptly inflated; sandy to loamy soils in prairies; at western edge of range neNM (UN), also scTX to neWY, ND & IN; about 5100 ft (in NM); Jun P grandiflous
25 Plants usually < 5 dm tall; calyx lobes usually < 7 mm long; flowers 14-20 mm long; inflorescence congested; corolla pale lavender-blue; sandy soil in grasslands; eNM (CH, ED, LE, RO), TX, seCO, wKS; 3500-4500 ft; May-Jun P buckleyi
26 Corollas pale blue to bluish-purple; prairies & hills in nNM (CO, MC, SJ, TA, UN), seCO, wKS, wOK (southern Great Plains); 4000-8500 ft; May-Jun P angustifolius caudatus
26 Corollas lavender to pinkish; sandy soils in blackbrush, sagebrush, PJ in nwNM (SJ), seUT, neAZ (Colorado Plateau); 5000-5800 ft; May-Jun P angustifolius venosus
27 Inflorescence not secund; bracts broadly ovate with a short, abruptly pointed tip; throat narrow and often somewhat curved, expanded only a the orifice, glabrous at base of lower lobes; prairies & lower mts in NM (CH, DA, DB, GR, GU, HA, HI, LE, LI, LU, MO, QU, SA, SI, SM, SO), swKS, wOK, wTX, seAZ, Chihuahua; about 4000-7000 ft; Apr-Jun P fendleri
27 Inflorescence at least more-or-less secund, usually distinctly so; bracts lanceolate; throat gradually expanded, usually bearded at base of lower lobes; staminode bearded, tip dilated [the following not always easy to distinguish] >28
28 Calyx margins broadly scarious, often pinkish or purplish; inflorescence usually strongly secund; pedicels & peduncles usually short; rocky areas in wc, c, nc & neNM (BE, CA, CO, HA, LA, MC, SA, SF, SM, TA, UN), sCO, sWY; 5000-9500 ft; May-Jun P secundiflorus
28 Calyx margins narrowly scarious, usually not colored; inflorescence more-or-less secund; peduncles & pedicels usually elongate; sandy or gravelly soils in sagebrush, PJ, oak, PIPO in nwNM (MC, SJ), seUT, swCO, neAZ; 4900-8500 ft; May-Jun; RARE P lentus lentus
29 Inflorescence and corollas glandular pubescent externally >30
29 Inflorescence not glandular (glabrous or puberulous) >43
30 Fascicles of small, obscurely toothed leaves in axils of stem leaves; corolla abruptly ampliate ventricose, violet to purple color; anthers fully dehiscent but not explanate; staminode dilated distally, yellow bearded; rocky areas at middle elevations in swNM (HI) to scMEX P campanulatus chihuahensis
30 No fasciculate leaves (fascicles of leaves occasionally present in P. dasyphyllus, but then leaves much longer & not toothed and staminode glabrous & not dilated) >31
31 Anther sacs explanate >32
31 Anther sacs not explanate >37
32 Corolla dull purple (rarely white), lower lobes projecting, 3-5 mm longer than upper lobes; subalpine to above timberline in NM (BE, CA, LI, MO, RA, SA, SF, SI, TA, TO, VA), AZ, CO, UT, WY, selD, swMT;8200-11,800 ft; Jun-Aug (Sep) P whippleanus
32 Corolla white, pale lavender, violet-blue, blue-purple, lower lobes not projecting, not noticeably longer than upper lobes >33
33 Corolla not bearded at base of lower lobes; staminode sparsely to moderately bearded >34
33 Corolla bearded at base of lower lobes; staminode conspicuously bearded >35
34 Corolla 1-2 cm long, densely glandular pubescent within and without, white (rarely pale lavender); tube funnel form & moderately inflated; western Great Plains; NM (QU, UN) to TX & sCAN; about 5000 ft; May-Jun P albidus
34 Corolla 3.6-6 cm long, pale colored, densely glandular pubescent without but glabrous within; tube abruptly inflated; prairies, pastures, hills; escaped in NM (QU, TA) & seCO, native range in NB, MO, AR, OK, eTX; 3800-7200 ft; Apr-Jun P cobaea
35 Corolla 5-6 mm wide, orifice as high or higher than wide; lower lip not glandular within; staminode not or barely exserted; throat not to moderately inflated; shrub land, PJ in nwNM (MC, SJ), swCO, seUT; 5200-7600 ft; May-Jun P breviculus
35 Corolla 8-19 mm wide, orifice much wider than high; lower lip glandular within; staminode usually prominently exserted; throat much inflated >36
36 Corolla 24-35 mm long, 10-15 mm wide; plains in NM (BE, CO, CU, DB, ED, GU, LI, MO, OT, QU, RO, SA, SF, SM, TO, UN), seCO, swKS, wTX; 4200-8000 ft; May-Jun P jamesii
36 Corolla 14-22 mm long, 8-19 mm wide; wNM (CA, CI, MC, SI, SJ, VA), swCO, nAZ, sUT (Colorado Plateau); 4900-7400 ft; Jun-Aug P ophianthus
37 Staminode glabrous, not dilated at tip; corolla markedly ampliate; anthers U-shaped, sutures spinescent; leaves occasionally in fascicles; gravelly slopes, desert grasslands in swNM (HI, LU), seAZ, Big Bend, ncMEX; 4500-5700 ft; Jun-Aug P dasyphyllus
37 Staminode bearded; corolla narrow to expanded; anthers not U-shaped & not spinescent; leaves never in fascicles >38
38 Leaves finely toothed; corolla pale lavender to pale violet; corolla floor narrow, 2-ridged; base of lower lobes white hairy; plains in neNM (CO, SM, UN), seCO, to CAN, WI (eastern slope of Rockies); 7000-8700 ft; Jun-Aug P gracilis
38 Leaves entire or undulate (occasionally denticulate in P. auriberbis); corollas darker in color; corolla floor ridged or not, base of lower lobes usually hairy >38
39 Corolla floor without ridges on under side; base of lower lobes villous; corolla 14-24 mm long, staminode slightly included to distinctly exserted, densely golden bearded for most its length, dilated at tip; bracts leaf-like and not much reduced; plains in neNM (CO, UN, barely enters NM) & seCO (common); 4500-7500 ft; May-Jun P auriberis
39 Corolla floor deeply to moderately ridged on under side; base of lower lobes with a few white or many yellow hairs; staminode usually included, densely bearded for half its length; bracts always reduced and never leaf-like >40
40 Corolla floor deeply 2-ridged; base of lower lobes & floor of corolla and staminode densely covered with golden hairs; corolla 17-25 mm; flowers drooping to horizontal; rocky areas in forests & grasslands in neNM (RA, TA), seCO; 7000-10,000 ft P griffinii
40 Corolla floor less strongly ridged, glabrous; base of lower lobes with a few white hairs; staminode orange-bearded; corolla 11-27 mm; flowers ascending to drooping [these three not always readily distinguishable] >41
41 Corolla fairly abruptly but moderately inflated, 17-27 mm long; flowers ascending to horizontal; plants robust (1-6 dm); basal rosette usually gone at anthesis; all but uppermost cauline leaves usually well-developed & similar to basal; hillsides & meadows in c & ncNM (BE, CO, SF, SM, TA, TO); 7500-11,000 ft; (May) Jun-Aug P inflatus
41 Corolla straight or little inflated, 11-20 mm long; plants smaller (1-4 dm); basal rosette often present at anthesis; basal leaves best developed; cauline leaves usually smaller than basal >42
42 Stems obviously puberulent; flowers mostly ascending, never drooping; corollas not inflated; floor obscurely ridged; plants 1-3 dm tall; basal rosette persistent; subalpine meadows in San Mateo & Magdalena Mts (SO); 9500-10,100 ft; Jul-Aug (Oct); RARE P pseudoparvus
42 Stems obscurely puberulent; flowers drooping to horizontal, never ascending; corollas little inflated; floor moderately ridged; plants 1.5-4 dm tall; basal rosette present or absent at anthesis; meadows & moist woods in wc & ncNM (CA, CI, MC, SA, SO) to ecAZ (White Mts); 8200-11,400 ft; Jun-Aug P oliganthus
43 Inflorescence not at all secund; flowers 10-14 mm long, in dense fascicles usually separated by long intemodes; slopes, meadows, forests in nNM (CO, RA, SA, SJ, TA), nAZ, wCO, neUT, seWY; 7000-10,800 ft; Jul-Aug (Sep) P rydbergii
43 Inflorescence at least somewhat secund, often distinctly so; flowers 15 40 mm long, not in dense fascicles, or if so, the fascicles not separated by long intemodes >44
44 Leaves large & broad, lance ovate or oblong; inflorescence usually broad and compact; corolla 30-40 mm long; stems usually densely leafy; plains & low mountains in neNM (CO, UN) & seCO; 5200-6700 ft; Jun-Aug P. glaber brandegei
44 Leaves linear or lanceolate; inflorescence usually narrow and elongated; corolla 15-38 mm long >45
45 Anthers glabrous, not explanate; staminode hairy or glabrous >46
45 Anthers pubescent (sometimes very sparsely), not opening proximal 1/6 1/4, sutures spinescent; staminode glabrous to short bearded >49
46 Staminode with tuft of golden hairs at tip; corolla blue purple, violet purple, occasionally paler, 16-25 mm, base of lower lobes white bearded; sepals 4-9mm; NM (CA, CI), ecAZ (fairly common); 7500-11,280 ft; Jul-Sep; RARE P deaveri
46 Staminode glabrous >47
47 Corolla 25-35 mm long, 10-17 mm wide, usually strongly white bearded at base of lower lobes; sepals 4-8 mm long; plants glabrous; MM (LI, OT) endemic to Capitan & Sacramento Mts, but not rare; 6000-9000 ft; Jul-Aug P neomexicanus
47 Corolla 17-28 mm long, 7-10 mm wide, glabrous or lightly white bearded at base of lower lobes; sepals 2-4 mm long >48
48 Plants puberulous; mountain valleys & hillsides in nc, wc, swNM (BE, CA, CO, GR, LU, MC, RA, SA, SF, SI, M, TA, TO) & ncAZ; 7000-11,000 ft; Jul-Aug P virgatus virgatus
48 Plants glabrous; uncommon in ncNM (CO) but abundant in Front Range, CO; 5500-9500 ft; Jul P virgatus asa-grayi
49 Inflorescence usually broader, cymes often much-branched, peduncles & pedicels elongate & divaricate; pollen sac sides villous or lanate, hairs to 2.5 mm; cauline leaf blades oblanceolate to linear; corolla pale blue to lavender, 25-38 mm long; sagebrush, PJ, oak, PIPO in nwNM (SJ), swCO, UT, neAZ, NV; 5200-9000 ft; Jun-Aug P comarrhenus
49 Pollen sac sides villous or lanate, hairs to 1.8 mm; cauline leaf blades lanceolate or linear; corollas blue, lavender, violet, or purple >50
50 Anthers with flexuous hairs to 1 mm (less than length of sac); staminode short bearded on distal half; calyx 5-9 mm long, segments usually lanceolate, acuminate or caudate, lower margins scarious, erase; corolla lavender to blue, without nectar guides, 19-32 mm long; nwNM (RA, SJ), seUT, swCO,neAZ; 5500-9200 ft; Jun-Aug P strictiformis
50 Anthers moderately to densely lanate to villous, hairs to 1.8 mm (greater than or equaling the length of the sac); anthers less densely pubescent than P. comarrhenus; staminode glabrous or with a few hairs at the tip; calyx 3-5 mm long, segments usually ovate, rounded; corolla purple to violet or blue, with violet nectar guides, 18-32 mm long; plains, meadows, wooded slopes in sagebrush, oak, PJ, PIPO & fir in NM (BE, CA, CI, CO, MC, RA, SA, SJ, TA, TO), neAZ, CO, UT, WY; 7200-10,500 ft; Jun-Aug P strictus
Posted by egordon88 egordon88, 09 September, 2021 18:56


Hi! Thank you so much for posting this key to Penstemon species.

I was trying to identify a Penstemon using your key, and I saw that there are three of number 49. It looks to me like something might not be quite right with the formatting there. Would you mind taking a look at that?

Thank you,

Posted by jdietrch over 1 year ago (Flag)

Update: the key is missing Penstemon bleaklyi, which should split off around step 32 with Penstemon whippleanus. Rare alpine wildflower in Taos County and adjacent Culebra Range of southern Colorado.

Posted by egordon88 over 1 year ago (Flag)

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