Penstemon sect. Coerulei
Penstemon subg. Penstemon
glabrous, sometimes scabrous, glaucous.
basal and cauline, sometimes basal absent or reduced, opposite, leathery, glabrous, rarely scabrous, glaucous;
basal and proximal cauline petiolate, sometimes short-petiolate (P. immanifestus, P. lentus);
cauline sessile, sometimes short-petiolate, blade obovate, ovate, spatulate, trullate, oblanceolate, lanceolate, oblong, elliptic, linear, or orbiculate, margins entire.
continuous or interrupted, cylindric, sometimes secund, axis glabrous, rarely scabrous or glutinous, cymes 2 per node;
peduncles and pedicels ascending to erect.
calyx lobes: margins entire or erose, herbaceous or ± scarious, glabrous, rarely scabrous, glandular, glandular-pubescent, or glutinous;
corolla lavender to blue, violet, purple, or pink, rarely white or red, bilaterally symmetric, rarely nearly radially symmetric (P. cyathophorus), weakly, rarely strongly, bilabiate, not personate, tubular-funnelform, funnelform, or weakly ventricose, rarely tubular-salverform or weakly ampliate, glabrous externally, rarely obscurely glandular, glabrous or hairy internally abaxially, throat slightly to abruptly inflated, not constricted at orifice, rounded abaxially, rarely slightly 2-ridged;
stamens included to exserted, filaments glabrous, pollen sacs opposite, rarely divergent or parallel, navicular, rarely explanate (P. murrayanus), dehiscing completely, connective splitting, sides glabrous, sutures papillate, sometimes smooth;
staminode included to exserted, flattened distally, (0.2–)0.4–3 mm diam., tip recurved, rarely coiled or straight, distal 10–50(–70)% hairy, hairs to 2.5 mm, rarely glabrous;
style glabrous.
pollen sacs navicular, navicular-sigmoid, saccate, or explanate, dehiscing completely or incompletely, connective splitting or not, sides glabrous or hairy, hairs not concealing surface, sutures smooth, papillate, or denticulate;
staminode included to exserted, if included, length 3/4+ times corolla throat.
glabrous.
brown or dark brown, angled, angled-elongate, or disciform, 1.8–5.4 mm.
angled or rounded, rarely angled-elongate, reniform, or disciform, wings absent.
Penstemon sect. Coerulei
Penstemon subg. Penstemon
Species 20 (20 in the flora).
D. D. Keck (1951) proposed the section name Anularius for sect. Coerulei, believing that the name of Pennell was invalid. N. H. Holmgren (1979b) concluded that the section names of Pennell are valid and that sect. Anularius Keck is invalid; the new combinations by Keck in that publication lacked descriptions.
Members of sect. Coerulei usually are recognized by their mostly glabrous, glaucous, and fleshy herbage, their blue or pink corollas that are glabrous, rarely obscurely glandular, externally, and their relatively broad and heavily bearded staminodes. Penstemon murrayanus has red corollas and glabrous staminodes. Members of sect. Coerulei mostly occur on well-drained, sandy soils. Molecular data (C. A. Wessinger et al. 2016) support the monophyly of the section.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species ca. 270 (229 in the flora).
Following the recommendation of A. D. Wolfe et al. (2006), subg. Penstemon is expanded here to include species of Penstemon not included in subg. Dasanthera. Molecular data indicate that some sections as usually circumscribed are paraphyletic. Absent a robust phylogeny for Penstemon, a morphology-based classification is followed here with minor adjustments. As circumscribed here, subg. Penstemon comprises 16 sections, 15 in the flora area.
Section Leptostemon Trautvetter includes 27 species from Mexico and Guatemala. Among its members are Penstemon campanulatus (Cavanilles) Willdenow, P. gentianoides (Kunth) Poiret, and P. hartwegii Bentham, three red- or purple-flowered species popular among European plant breeders in the nineteenth century and used in the development of European hybrid penstemons (R. Nold 1999; D. Lindgren and E. Wilde 2003).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Corollas red; staminodes glabrous; pollen sacs explanate. | P. murrayanus |
1. Corollas lavender to blue, violet, purple, or pink, rarely white; staminodes hairy; pollen sacs navicular. | → 2 |
2. Pollen sacs parallel or divergent; stamens: 2 or 4 prominently exserted; corollas without nectar guides. | → 3 |
3. Stamens: 4 exserted; pollen sacs 1.2–1.5 mm; corollas 11–14 mm. | P. cyathophorus |
3. Stamens: 2 exserted; pollen sacs 2–3 mm; corollas 17–24 mm. | P. harringtonii |
2. Pollen sacs opposite or divergent; stamens included or longer pair reaching orifice to slightly exserted; corollas usually with nectar guides. | → 4 |
4. Corollas 21–48 mm, ampliate, glabrous internally, throats abruptly inflated. | → 5 |
5. Corollas 35–48 mm; cauline leaf blades spatulate to orbiculate. | P. grandiflorus |
5. Corollas 21–28 mm; cauline leaf blades lanceolate to linear. | P. haydenii |
4. Corollas 10–25(–28) mm, tubular-funnelform, tubular-salverform, funnelform, or ventricose, white-villous internally abaxially or glabrous, throats not abruptly inflated. | → 6 |
6. Corollas tubular-salverform; thyrses interrupted. | P. fendleri |
6. Corollas tubular-funnelform, funnelform, or ventricose; thyrses continuous or interrupted. | → 7 |
7. Stems 3–10(–15) cm; cauline leaf pairs 1–3; thyrses 1–6 cm; verticillasters 1–5(or 6). | P. bracteatus |
7. Stems (4–)7–77(–82) cm; cauline leaf pairs 1–8(or 9); thyrses (2–)3–37(–57) cm; verticillasters (2 or)3–20(–35). | → 8 |
8. Thyrses secund. | → 9 |
9. Cauline leaves 2–4 pairs; staminodes 8–9 mm, distal 3–4 mm sparsely to densely villous, hairs yellowish, to 1 mm; Arizona, Colorado, New Mexico, Utah. | P. lentus |
9. Cauline leaves 4–6 pairs; staminodes 10–13 mm, distal 4–6 mm densely villous, hairs golden yellow, to 2 mm; Colorado, New Mexico, Wyoming. | P. secundiflorus |
8. Thyrses cylindric. | → 10 |
10. Staminodes 2–3 mm diam.; corollas with nectar guides, sparsely to moderately white-villous internally abaxially, rarely glabrous. | P. osterhoutii |
10. Staminodes (0.2–)0.4–2 mm diam.; corollas with or without nectar guides, glabrous or sparsely white-villous internally abaxially. | → 11 |
11. Corollas pink or white. | → 12 |
12. Corollas white. | P. lentus |
12. Corollas pink. | → 13 |
13. Leaves: basal usually reduced or absent; corollas glabrous internally; staminodes: distal 0.5–1.5 mm lanulose, hairs to 0.6 mm. | P. flowersii |
13. Leaves: basal not reduced; corollas sparsely white-hairy internally abaxially or glabrous; staminodes: distal 2–6 mm villous, hairs to 1 mm. | → 14 |
14. Cauline leaf apices acute to acuminate; corollas tubular-funnelform; calyx lobes ovate to lanceolate, 4–8 × 1–2.5 mm. | P. angustifolius |
14. Cauline leaf apices obtuse to acute; corollas funnelform to ventricose; calyx lobes ovate, 5–8(–12) × 2–3.5 mm. | P. immanifestus |
11. Corollas blue, pinkish blue, lavender-blue, lavender, violet, or purple, rarely some individuals with corollas pink. | → 15 |
15. Cauline leaf blades ovate to orbiculate; corollas with nectar guides, villous internally abaxially. | P. mucronatus |
15. Cauline leaf blades elliptic to ovate, obovate, lanceolate, oblanceolate, or linear; corollas with or without nectar guides, glabrous or villous internally abaxially. | → 16 |
16. Stems decumbent to ascending, (4–)7–18(–30) cm; thyrses continuous; proximal bracts oblanceolate to lanceolate; corollas (10–)12–15 mm; pollen sacs 0.7–0.8 mm. | P. arenicola |
16. Stems ascending to erect, (5–)9–60(–82) cm; thyrses interrupted or continuous; proximal bracts orbiculate to ovate, lanceolate, oblong, or linear; corollas 10–22 mm; pollen sacs 0.7–1.6 mm. | → 17 |
17. Proximal bracts orbiculate to ovate; corollas lavender to bluish lavender or pinkish blue, glabrous internally; capsules 12–18(–20) mm. | P. buckleyi |
17. Proximal bracts ovate to oblong, lanceolate, or linear, rarely orbiculate; corollas blue, pinkish blue, bluish lavender, violet, or purple, hairy internally abaxially or glabrous; capsules 7–15 mm. | → 18 |
18. Corollas obscurely glandular externally or glabrous; cauline leaves 1–3 pairs; thyrses 3–15 cm, continuous, sometimes interrupted. | P. carnosus |
18. Corollas glabrous externally; cauline leaves 2–8 pairs; thyrses (2–)5–30(–37) cm, continuous or interrupted. | → 19 |
19. Staminodes 1–2 mm diam., distal 6–8 mm villous, hairs to 2.5 mm. | P. pachyphyllus |
19. Staminodes (0.2–)0.5–1.5 mm diam., distal 1.5–7 mm pilose to villous, hairs to 1.5 mm. | → 20 |
20. Cauline leaf blades: apices obtuse to acute, sometimes rounded or mucronate; peduncles to 12–28 mm; corolla throats 5–8 mm diam. | → 21 |
21. Cymes 1–3(or 4)-flowered; cauline leaves sessile; seeds 3.5–5 mm. | P. lentus |
21. Cymes (1 or)2–6-flowered; cauline leaves short-petiolate or sessile; seeds 2–4 mm. | → 22 |
22. Corollas bluish lavender to lavender, 15–22 mm; peduncles to 12 mm; calyx lobes ovate, 5–8(–12) mm, apices acuminate; staminodes: distal 2–5 mm densely villous, hairs yellowish, brownish, or orangish, to 1 mm. | P. immanifestus |
22. Corollas blue to violet, sometimes lavender, 12–20 mm; peduncles to 26 mm; calyx lobes ovate to lanceolate, (2.5–)4–7 mm, apices acute to acuminate or caudate; staminodes: distal 4–8 mm densely villous, hairs yellow to golden yellow, to 2.5 mm. | P. pachyphyllus |
20. Cauline leaf blades: apices acute to acuminate, sometimes mucronate (P. nitidus); peduncles to 3–4 mm; corolla throats 4–6 mm diam. | → 23 |
23. Cymes 2–5-flowered, verticillasters (2–)4–10; corolla tubes 4–6 mm; stems glabrous. | P. nitidus |
23. Cymes (2–)4–8(–12)-flowered, verticillasters (3–)5–15(–26); corolla tubes 5–9 mm; stems glabrous or scabrous. | → 24 |
24. Staminodes: distal 1.5–3.5 mm densely pilose, hairs to 0.6 mm; calyx lobes lanceolate, (3.2–)4.5–10 × 1.2–3.2(–3.8) mm; pollen sacs 0.7–1.3(–1.5) mm; Idaho, Nevada, Oregon, Washington. | P. acuminatus |
24. Staminodes: distal 4–6 mm sparsely villous, hairs to 1 mm; calyx lobes ovate to lanceolate, 4–8 × 1–2.5 mm; pollen sacs (0.9–)1.1–1.5 mm; Arizona, Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Utah, Wyoming. | P. angustifolius |
Key to Sections of subg. Penstemon
1. Cauline leaf blade margins deeply pinnatifid to nearly pinnatisect. | P. sect. Dissecti |
1. Cauline leaf blade margins entire or toothed, rarely laciniate-pinnatifid. | → 2 |
2. Subshrubs or shrubs; staminodes glabrous; corollas pink, red, scarlet, or magenta, rarely lavender or violet. | → 3 |
3. Cauline leaf blades linear and pollen sacs explanate. | P. sect. Ambigui |
3. Cauline leaf blades obovate, ovate, oblanceolate, lanceolate, elliptic, or linear; pollen sacs navicular, saccate, subexplanate, or explanate. | → 4 |
4. Pollen sacs subexplanate to explanate, opposite; corollas weakly ventricose; thyrses cylindric; leaves glaucous. | P. sect. Petiolati |
4. Pollen sacs saccate or navicular, parallel or divergent; corollas salverform or funnelform; thyrses secund; leaves not glaucous. | → 5 |
5. Cauline leaf margins toothed or entire; corollas funnelform, glandular-pubescent internally abaxially and adaxially; cymes 1 per node; Texas. | P. sect. Baccharifolii |
5. Cauline leaf margins entire; corollas salverform, hairy internally abaxially; cymes 2 per node; Arizona, California, Colorado, Nevada, New Mexico, Utah. | P. sect. Bridgesiani |
2. Herbs, shrubs, or subshrubs; staminodes hairy distally or glabrous; corollas usually white, lavender, lilac, blue, violet, purple, ochroleucous, yellow, orange, or crimson, if pink, red, scarlet, or magenta, herbs and/or staminodes hairy, or both. | → 6 |
6. Pollen sacs saccate, dehiscing incompletely, distal 1/5–2/3 indehiscent, connectives splitting, rarely not. | → 7 |
7. Pollen sac sutures papillate; herbs. | P. sect. Penstemon |
7. Pollen sac sutures denticulate; herbs or subshrubs. | → 8 |
8. Herbs; pollen sac sides glabrous; staminodes glabrous, tips recurved; cauline leaf blade margins entire; thyrses interrupted. | P. sect. Chamaeleon |
8. Herbs or subshrubs; pollen sac sides glabrous or hairy; staminodes glabrous or hairy distally, tips straight; cauline leaf blade margins entire or toothed, rarely laciniate-pinnatifid; thyrses interrupted or continuous. | P. sect. Saccanthera |
6. Pollen sacs navicular, navicular-sigmoid, sigmoid, subexplanate, or explanate, dehiscing completely, if incompletely proximal 1/5–1/2 indehiscent and/or connectives not splitting. | → 9 |
9. Pollen sacs dehiscing incompletely, proximal 1/5–1/2 indehiscent and/or connectives not splitting. | → 10 |
10. Corollas red to scarlet or orange, rarely yellow, glabrous externally. | P. sect. Elmigera |
10. Corollas white to pink, lavender, lilac, blue, violet, or purple, glandular-pubescent or glabrous externally, if corollas reddish pink or rose red, glandular-pubescent externally. | → 11 |
11. Pollen sacs: connectives not splitting, sutures papillate, sides glabrous; corollas tubular-funnelform. | P. sect. Cristati |
11. Pollen sacs: proximal 1/5–1/3 indehiscent and/or connectives not splitting, sutures denticulate, sometimes papillate or smooth, sides glabrous or hairy; corollas funnelform, ventricose, or ventricose-ampliate. | P. sect. Glabri |
9. Pollen sacs dehiscing completely (rarely connectives not splitting in P. incertus). | → 12 |
12. Staminodes glabrous; pollen sacs parallel to divergent, sutures denticulate, teeth to 0.2–0.3 mm. | P. sect. Chamaeleon |
12. Staminodes hairy distally, sometimes glabrous; pollen sacs opposite or divergent, rarely parallel, sutures smooth, papillate, or denticulate, teeth to 0.1–0.2 mm. | → 13 |
13. Subshrubs; leaves cauline, rarely basal and cauline, blade margins entire; stems not glaucous; corollas 2-ridged abaxially. | P. sect. Caespitosi |
13. Herbs, shrubs, or subshrubs; leaves basal and cauline, sometimes basal few or absent, blade margins entire or toothed, if shrubs or subshrubs, leaves basal and cauline or leaf blade margins toothed or stems glaucous; corollas rounded to 2-ridged abaxially. | → 14 |
14. Stems and/or leaves and/or thyrse axes hairy; leaf blades not (or rarely) glaucous, not (or rarely) leathery. | → 15 |
15. Corollas glabrous externally, ventricose or ventricose-ampliate. | P. sect. Glabri |
15. Corollas glandular-pubescent externally, if glabrous then tubular, tubular-funnelform, or funnelform. | → 16 |
16. Corolla throats rounded abaxially, sometimes slightly 2-ridged; staminodes: distal (40–)50–100% hairy, hairs to 4 mm, exserted, sometimes reaching orifice or included, tips straight to recurved or coiled; seeds 1.4–4.8 mm, brown, dark brown, or black. | P. sect. Cristati |
16. Corolla throats slightly to prominently 2-ridged abaxially, rarely rounded; staminodes: distal 5–60(–90)% hairy, hairs to 3 mm, sometimes glabrous, included or reaching orifice, sometimes exserted, tips straight to recurved; seeds 0.4–2(–3.5) mm, tan, brown, gray, or black. | P. sect. Penstemon |
14. Stems, leaves, and thyrse axes glabrous, rarely scabrous; leaf blades glaucous, rarely not, leathery, rarely not. | → 17 |
17. Shrubs or subshrubs; stamen filaments: shorter pair glandular-puberulent proximally. | P. sect. Spectabiles |
17. Herbs; stamen filaments glabrous. | → 18 |
18. Leaf blade margins toothed. | P. sect. Spectabiles |
18. Leaf blade margins entire (rarely remotely and obscurely toothed in P. parryi). | → 19 |
19. Stamens exserted; corollas red, 32–36 mm. | P. sect. Coerulei |
19. Stamens included or longer pair reaching orifice, rarely exserted; corollas lavender to blue, violet, purple, white, pink, lilac, red, scarlet, crimson, magenta, orange, yellow, or ochroleucous, 6–33 mm. | → 20 |
20. Basal and proximal cauline leaf blades linear, 0.5–1.5 mm wide. | P. sect. Cristati |
20. Leaf blades ovate, obovate, lanceolate, oblanceolate, spatulate, trullate, oblong, or elliptic, rarely linear, 1–70 mm wide. | → 21 |
21. Pollen sacs 0.3–1.2 mm, opposite; corollas 7–22 mm, throats 2-ridged abaxially, sometimes rounded. | P. sect. Penstemon |
21. Pollen sacs 0.6–3 mm, opposite, divergent, or parallel; corollas 10–48 mm, throats rounded abaxially, rarely slightly 2-ridged. | → 22 |
22. Pollens sacs navicular; corollas glabrous externally, rarely obscurely glandular (P. carnosus). | P. sect. Coerulei |
22. Pollen sacs explanate, sometimes navicular; corollas glandular-pubescent externally, if glabrous staminode papillate distally, papillae to 0.2 mm. | P. sect. Gentianoides |
