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Habit Herbs.
Stems

glabrous, retrorsely hairy, canescent, glandular, or glandular-pubescent, rarely glutinous, glaucous or not.

Leaves

basal and cauline, sometimes basal absent or reduced, opposite, leathery or not, glabrous, glabrescent, scabrous, puberulent, retrorsely hairy, or glandular-pubescent, glaucous or not;

basal and proximal cauline petiolate, sometimes short-petiolate (P. gibbensii, P. idahoensis);

cauline sessile or petiolate, blade obovate, ovate, spatulate, oblanceolate, elliptic-lanceolate, lanceolate, elliptic, oblong, or linear, margins entire.

Thyrses

continuous or interrupted, cylindric, subsecund, or secund, axis glabrous, glandular-pubescent, puberulent, or retrorsely hairy, rarely glandular, cymes 1 or 2 per node;

peduncles and pedicels ascending or erect, sometimes spreading (P. comarrhenus, P. cyananthus, P. nudiflorus).

Flowers

calyx lobes: margins erose or entire, rarely lacerate (P. hallii), ± scarious, glabrous or glandular-pubescent, sometimes glandular, glutinous, or puberulent;

corolla white to pink, lavender, blue, violet, or purple, bilaterally symmetric, weakly bilabiate to strongly bilabiate, not personate, funnelform, ventricose, or ventricose-ampliate, glabrous or glandular-pubescent externally, glabrous or hairy internally abaxially, rarely glandular-pubescent internally abaxially or adaxially, throat gradually to abruptly inflated, slightly constricted or not at orifice, rounded to 2-ridged abaxially;

stamens included or longer pair reaching orifice or exserted, filaments glabrous, pollen sacs divergent to opposite, navicular, navicular-sigmoid, or sigmoid, rarely subexplanate, dehiscing incompletely proximal 1/5–1/3 indehiscent, rarely completely, connective splitting or not, sides glabrous, papillate, or hairy, sutures denticulate, teeth to 0.1–0.2 mm, sometimes papillate or smooth;

staminode included to exserted, flattened distally, 0.2–1.3 mm diam., tip straight to recurved, distal 5–60(–90)% hairy or papillate, hairs or papillae to 1.5 mm, rarely glabrous;

style glabrous.

Capsules

glabrous.

Seeds

tan to brown or dark brown, angled to angled-elongate, 0.9–4 mm.

Penstemon sect. Glabri

Distribution
w United States; n Mexico
Discussion

Species 44 (43 in the flora).

Pollen sacs dehiscing from their distal ends proximally and connectives usually not splitting has traditionally been used as a synapomorphy for subg. Habroanthus (F. S. Crosswhite 1967). Within subg. Habroanthus, species with blue or violet and tubular or ventricose corollas have been included in sect. Glabri; species with red and tubular corollas have been placed in sect. Elmigera. Molecular studies (A. D. Wolfe et al. 2006; C. A. Wessinger et al. 2016) revealed that the four red-flowered species of sect. Elmigera in the flora area are closely related to blue-flowered species of sect. Glabri. Penstemon galloensis G. L. Nesom, known from Nuevo León, Mexico, is the only member of sect. Glabri occurring strictly outside the flora area.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Pollen sac sides glabrous.
→ 2
2. Corollas glandular-pubescent externally.
→ 3
3. Stems glabrous; leaves glabrous.
P. leiophyllus
3. Stems retrorsely hairy or puberulent to pubescent; leaves retrorsely hairy.
→ 4
4. Corollas 13–20 mm; pollen sacs 1–1.4 mm, navicular; styles 11–15 mm.
P. parvus
4. Corollas 24–30 mm; pollen sacs 2–2.5 mm, sigmoid; styles 20–24 mm.
P. wardii
2. Corollas glabrous externally, rarely glutinous and covered with sand.
→ 5
5. Stems glutinous and covered with sand, usually ± fistulose.
P. ammophilus
5. Stems glabrous or retrorsely hairy, puberulent, pubescent, canescent, or glandular-pubescent, not glutinous and covered with sand, not fistulose.
→ 6
6. Basal and proximal cauline leaf blades linear.
→ 7
7. Stems retrorsely hairy; corollas glabrous internally.
P. pseudoputus
7. Stems glabrous; corollas sparsely white-lanate internally abaxially.
P. putus
6. Basal and proximal cauline leaf blades ovate to elliptic, obovate, oblanceolate, lanceolate, or spatulate, rarely linear (P. virgatus).
→ 8
8. Stems glaucous; thyrses interrupted; peduncles and pedicels spreading to ascending; pollen sacs dehiscing completely.
P. nudiflorus
8. Stems slightly or not glaucous; thyrses continuous or interrupted; peduncles and pedicels ascending to erect; pollen sacs dehiscing incompletely or completely.
→ 9
9. Thyrse axes glandular-pubescent.
→ 10
10. Corollas 14–25 mm; pollen sacs navicular to subexplanate, 1.2–1.4 mm, dehiscing completely.
P. hallii
10. Corollas 25–35 mm; pollen sacs sigmoid, (1.8–)2–3 mm, dehiscing incompletely.
P. speciosus
9. Thyrse axes glabrous or retrorsely hairy.
→ 11
11. Pollen sacs dehiscing incompletely, proximal 1/5–1/3 indehiscent, connectives not splitting.
→ 12
12. Calyx lobes (4–)4.5–11(–13.5) mm; pollen sacs sigmoid, (1.8–)2–3 mm.
→ 13
13. Stems glabrous; pollen sacs 2–2.5 mm, sides glabrous; staminodes: distal 5–7 mm ± pilose, hairs yellow, to 1 mm; capsules 8–10 mm.
P. laevis
13. Stems glabrous or retrorsely hairy; pollen sacs (1.8–)2–3 mm, sides glabrous or sparsely hispidulous; staminodes glabrous or distal 1–7 mm sparsely pilose, hairs yellow to yellowish orange, to 0.8 mm; capsules 10–16 mm.
P. speciosus
12. Calyx lobes 2.5–5 mm; pollen sacs navicular, navicular-sigmoid, or sigmoid, 1.2–2.2 mm.
→ 14
14. Staminodes glabrous; pollen sac sides lanate, rarely glabrous.
P. navajoa
14. Staminodes pilose distally; pollen sac sides glabrous.
→ 15
15. Corollas sparsely yellow- or white-villous internally abaxially; stems glabrous; pollen sacs sigmoid, 1.6–2.2 mm.
P. pahutensis
15. Corollas glabrous internally; stems glabrous or retrorsely hairy; pollen sacs navicular-sigmoid or navicular, 1.3–1.7 mm.
→ 16
16. Stems glabrous or retrorsely hairy; calyx lobes: margins broadly scarious, apices rounded to acute or mucronate; Idaho, Oregon.
P. perpulcher
16. Stems retrorsely hairy; calyx lobes: margins narrowly scarious, apices obtuse, sometimes acute to cuspidate; Utah.
P. tidestromii
11. Pollen sacs dehiscing completely or connectives not splitting.
→ 17
17. Staminodes pilose to lanate distally.
→ 18
18. Pollen sacs 1.2–1.5 mm, sutures smooth or papillate; staminodes: distal 0.5–2 mm sparsely to moderately pilose; styles 10–14 mm.
P. deaveri
18. Pollen sacs 1.2–2.5(–2.8) mm, sutures denticulate; staminodes: distal 1–8 mm pilose or lanate; styles 11–20 mm.
→ 19
19. Corollas 22–48 mm, glabrous or sparsely to moderately white-lanate internally abaxially.
P. glaber
19. Corollas 13–22 mm, glabrous internally.
→ 20
20. Stems glabrous.
P. payettensis
20. Stems retrorsely hairy.
P. tidestromii
17. Staminodes glabrous.
→ 21
21. Cauline leaves 1–5 mm wide; pollen sac sides lanate, hairs to 0.9 mm, rarely glabrous; stems glabrous.
P. navajoa
21. Cauline leaves 3–35(–43) mm wide; pollen sac sides glabrous or sparsely to moderately hirsute, hairs to 0.5 mm; stems glabrous or puberulent to pubescent.
→ 22
22. Pollen sac sutures denticulate; cauline leaves (6–)22–35(–43) mm wide.
P. glaber
22. Pollen sac sutures smooth or papillate; cauline leaves 3–17 mm wide.
→ 23
23. Stems glabrous; corollas sparsely to densely white-villous internally abaxially; New Mexico.
P. neomexicanus
23. Stems glabrous or puberulent; corollas sparsely white-villous internally abaxially, rarely glabrous; Arizona, Colorado, New Mexico, Wyoming.
P. virgatus
1. Pollen sac sides hairy.
→ 24
24. Corollas ± glandular-pubescent or glandular externally.
→ 25
25. Pollen sacs: proximal 1/5–1/4 indehiscent.
→ 26
26. Corollas 18–33 mm, throats 6–11 mm diam.; pollen sacs (1.3–)1.5–2.4 mm; styles 12–22 mm; stems glabrous.
P. scariosus
26. Corollas 14–18(–20) mm, throats 5–7 mm diam.; pollen sacs 1–1.7 mm; styles 9–16 mm; stems puberulent, pubescent, retrorsely pubescent, or glabrous.
→ 27
27. Thyrse axes glabrous; stems glabrous or ± puberulent proximally.
P. cyanocaulis
27. Thyrse axes glandular-pubescent; stems pubescent to retrorsely hairy, sometimes glabrous proximally, glandular-pubescent distally.
P. gibbensii
25. Pollen sacs: connectives not splitting.
→ 28
28. Stems 5–15(–24) cm; corollas without nectar guides.
P. uintahensis
28. Stems (10–)18–90(–130) cm; corollas with violet or reddish purple nectar guides.
→ 29
29. Staminodes: distal 7–9 mm sparsely to moderately villous; styles 9–11 mm.
P. mensarum
29. Staminodes: distal 2–5 mm sparsely villous; styles 14–18 mm.
→ 30
30. Stems glabrous; corollas glabrous or ± glandular-pubescent internally abaxially; Colorado, Wyoming.
P. saxosorum
30. Stems glabrous proximally, usually sparsely glandular distally; corollas glabrous internally; Idaho, Utah, Wyoming.
P. subglaber
24. Corollas glabrous externally.
→ 31
31. Stems glutinous, usually covered with sand.
→ 32
32. Corollas 20–28 mm; styles 17–20 mm; pollen sacs 2–2.5 mm, proximal 1/5 indehiscent, connectives not splitting; Montana, Wyoming.
P. caryi
32. Corollas 15–21 mm; styles 12–14 mm; pollen sacs 1.5–2 mm, connectives not splitting; Idaho, Nevada, Utah.
P. idahoensis
31. Stems glabrous or retrorsely hairy, puberulent, pubescent, cinereous, or glandular-pubescent.
→ 33
33. Caudices herbaceous, rhizomelike; corollas white to lavender; proximal bracts obovate to oblanceolate; stems 4–9 cm.
P. debilis
33. Caudices woody; corollas blue to bluish violet, violet, or purple, rarely pinkish blue or lavender; proximal bracts ovate to elliptic, oblong, lanceolate, or linear, rarely oblanceolate; stems 5–85(–120) cm.
→ 34
34. Thyrse axes glandular or glandular-pubescent, sometimes only distally, sometimes also retrorsely hairy.
→ 35
35. Corollas funnelform, 13–16 mm; styles 8–10 mm.
P. penlandii
35. Corollas ventricose, 14–35 mm; styles 10–23 mm.
→ 36
36. Pollen sacs navicular to subexplanate, 1.2–1.4 mm, dehiscing completely; calyx lobe margins erose or lacerate; corolla tubes 2–3 mm.
P. hallii
36. Pollen sacs navicular, navicular-sigmoid, or sigmoid, 1.1–3 mm, dehiscing incompletely; calyx lobe margins erose; corolla tubes 5–13 mm.
→ 37
37. Pollen sacs sigmoid or navicular-sigmoid, sides glabrous or hispidulous to hispid or pubescent, hairs to 0.3 mm; corollas 18–35 mm, tubes 7–13 mm; leaves retrorsely hairy or glabrous; calyx lobes (4–)6–12(–13.5) mm.
→ 38
38. Proximal bracts ovate to elliptic; pollen sacs: connectives not splitting; stems 7–27 cm.
P. absarokensis
38. Proximal bracts lanceolate, rarely ovate or linear; pollen sacs: proximal 1/5–1/3 indehiscent, connectives not splitting; stems 7–80(–90) cm.
→ 39
39. Pollen sacs 1.8–2.2 mm, sides sparsely hispid; stems retrorsely hairy; leaves retrorsely hairy.
P. lemhiensis
39. Pollen sacs (1.8–)2–3 mm, sides glabrous or sparsely hispidulous; stems glabrous or retrorsely hairy to pubescent; leaves glabrous or retrorsely hairy.
P. speciosus
37. Pollen sacs navicular, sides hispid, pubescent, or villous, hairs to 0.3–1 mm; corollas 17–33 mm, tubes 5–11 mm; leaves glabrous; calyx lobes 3.5–8 mm.
→ 40
40. Pollen sac sides hispid or pubescent, hairs to 0.3 mm.
P. saxosorum
40. Pollen sac sides pubescent to villous, hairs to 0.7–1 mm.
→ 41
41. Corollas 18–25 mm, tubes 5–7 mm; styles 14–17 mm; staminodes glabrous or distal 1–3 mm sparsely pilose, hairs yellow or white, to 0.5 mm.
P. compactus
41. Corollas 27–33 mm, tubes 9–11 mm; styles 17–21 mm; staminodes: distal 1–6 mm sparsely lanate, hairs yellowish, to 0.8 mm.
P. moriahensis
34. Thyrse axes glabrous, retrorsely hairy, or puberulent, not glandular or glandular-pubescent.
→ 42
42. Thyrse axes moderately to densely retrorsely hairy; corollas funnelform.
P. fremontii
42. Thyrse axes glabrous, puberulent, glandular-pubescent, or ± glandular; corollas ventricose, rarely ventricose-ampliate or funnelform.
→ 43
43. Pollen sac sides villous to lanate, rarely moderately pubescent, hairs to 0.7–2.5 mm.
→ 44
44. Corollas sparsely white-villous internally abaxially; staminodes glabrous.
P. navajoa
44. Corollas glabrous internally; staminodes glabrous or distal 1–6 mm pilose, villous, or lanate.
→ 45
45. Leaves: basal and proximal cauline blades oblanceolate to linear, cauline blades linear; calyx lobes (6–)7–12 mm.
P. caryi
45. Leaves: basal and proximal cauline blades oblanceolate to obovate, sometimes lanceolate, cauline blades oblanceolate to lanceolate or linear; calyx lobes (2.2–)3–8(–9) mm.
→ 46
46. Pollen sac sides villous or lanate, hairs to 2.5 mm; cauline leaf blades oblanceolate to linear; corollas blue to pinkish blue or lavender; thyrses interrupted, secund, sometimes subsecund.
P. comarrhenus
46. Pollen sac sides pubescent, villous, or lanate, hairs to 1.8 mm; cauline leaf blades oblanceolate to lanceolate or linear; corollas blue, lavender, violet, or purple; thyrses continuous or interrupted, cylindric or secund.
→ 47
47. Cauline leaf blades oblanceolate to lanceolate, rarely linear, apices obtuse to acute; proximal bracts oblong to lanceolate, apices acute to acuminate; peduncles to 7 mm, pedicels 1–11 mm.
→ 48
48. Corollas 18–25 mm, tubes 5–7 mm; styles 14–17 mm; staminodes glabrous or distal 1–3 mm sparsely pilose, hairs yellow or white, to 0.5 mm.
P. compactus
48. Corollas 27–33 mm, tubes 9–11 mm; styles 17–21 mm; staminodes: distal 1–6 mm sparsely lanate, hairs yellowish, to 0.8 mm.
P. moriahensis
47. Cauline leaf blades lanceolate to linear, apices acute or acuminate; proximal bracts lanceolate to linear, apices acuminate; peduncles to 20–27 mm, pedicels 1–20 mm.
→ 49
49. Calyx lobes (4.5–)6–8(–9) × 2–3 mm, apices acuminate to caudate; pollen sac sides sparsely to densely lanate, hairs to 1 mm; staminodes: distal (2–)4–5 mm sparsely to moderately villous, hairs yellow or white, to 1 mm.
P. strictiformis
49. Calyx lobes (2.5–)3–5 × 1.3–2.5 mm, apices acute, sometimes acuminate or obtuse; pollen sac sides moderately to densely lanate to villous, hairs to 1.8 mm; staminodes glabrous or distal 1–5 mm sparsely villous, hairs yellow or orange, to 0.7 mm.
P. strictus
43. Pollen sac sides hispidulous, hispid, pubescent, hirsute, or pilose, hairs to 0.1–1 mm, rarely glabrous.
→ 50
50. Pollen sacs navicular.
→ 51
51. Corollas 24–48 mm, throats 8–13(–18) mm diam.; pollen sacs 1.4–2.5(–2.8) mm, connectives not splitting.
P. glaber
51. Corollas 12–25(–30) mm, throats 4–11 mm diam.; pollen sacs 1.2–2(–2.2) mm, proximal 1/5–1/3 indehiscent, rarely only connectives not splitting.
→ 52
52. Staminodes reaching orifices or slightly exserted, distal 3–5 mm villous, hairs yellow, to 1 mm; stems erect; corolla tubes 5–8 mm, throats 6–8 mm diam.
P. saxosorum
52. Staminodes included or reaching orifices, distal 5–9 mm pilose to villous or lanate, hairs orange, yellow, or white, to 1 mm; stems decumbent, ascending, or erect; corolla tubes 5–11 mm, throats 4–11 mm diam.
→ 53
53. Cauline leaf blades ovate or oblanceolate to lanceolate, bases cordate-clasping to clasping; calyx lobe apices acute to acuminate or cuspidate; stems decumbent to erect, 5–70(–90) cm.
P. cyananthus
53. Cauline leaf blades oblanceolate to lanceolate or linear, bases tapered to truncate; calyx lobe apices acuminate, sometimes caudate; stems decumbent to ascending, 8–18(–25) cm.
P. paysoniorum
50. Pollen sacs sigmoid or navicular-sigmoid.
→ 54
54. Calyx lobes obovate to ovate, 2.5–4.5 mm, apices mucronate, sometimes acute to acuminate.
P. cyaneus
54. Calyx lobes ovate to lanceolate, rarely obovate, 3.5–12(–13.5) mm, apices acute to acuminate, cuspidate, or caudate.
→ 55
55. Calyx lobes (4–)6–12(–13.5) mm, glandular or glabrous; pollen sacs (1.8–)2–3 mm.
→ 56
56. Proximal bracts ovate to elliptic; pollen sacs: connectives not splitting; stems 7–27 cm.
P. absarokensis
56. Proximal bracts lanceolate, rarely ovate or linear; pollen sacs: proximal 1/3 indehiscent, connectives not splitting; stems 7–65(–90) cm.
P. speciosus
55. Calyx lobes 3.5–8.5 mm, glabrous; pollen sacs 1.2–2.7(–2.8) mm.
→ 57
57. Corollas 14–18(–20) mm; pollen sacs 1.2–1.7 mm, sides sparsely to moderately pilose, hairs to 0.5(–0.7) mm; calyx lobes 3.5–4.5 mm.
P. cyanocaulis
57. Corollas (20–)24–35 mm; pollen sacs 1.8–2.4(–2.8) mm, sides hirsute or hispid, hairs to 0.3 mm; calyx lobes 4.5–8.5 mm.
→ 58
58. Corollas (20–)24–30(–32) mm; staminodes: distal 0.5–1 mm moderately pilose, hairs to 0.8 mm, remaining distal 3–4 mm with scattered yellow hairs; cymes 1- or 2(or 3)-flowered.
P. longiflorus
58. Corollas 29–35 mm; staminodes: distal 4–6 mm ± uniformly sparsely pilose, hairs to 1 mm; cymes 1–6-flowered.
P. pennellianus
Source FNA vol. 17, p. 156.
Parent taxa Plantaginaceae > Penstemon > subg. Penstemon
Subordinate taxa
P. absarokensis, P. ammophilus, P. caryi, P. comarrhenus, P. compactus, P. cyananthus, P. cyaneus, P. cyanocaulis, P. deaveri, P. debilis, P. fremontii, P. gibbensii, P. glaber, P. hallii, P. idahoensis, P. laevis, P. leiophyllus, P. lemhiensis, P. longiflorus, P. mensarum, P. moriahensis, P. navajoa, P. neomexicanus, P. nudiflorus, P. pahutensis, P. parvus, P. payettensis, P. paysoniorum, P. penlandii, P. pennellianus, P. perpulcher, P. pseudoputus, P. putus, P. saxosorum, P. scariosus, P. speciosus, P. strictiformis, P. strictus, P. subglaber, P. tidestromii, P. uintahensis, P. virgatus, P. wardii
Synonyms P., P. subg. habroanthus
Name authority (Rydberg) Pennell: Contr. U.S. Natl. Herb. 20: 326, 329. (1920)
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