Penstemon sect. Caespitosi
Penstemon subg. Penstemon
retrorsely hairy, rarely glabrous, not glaucous.
cauline, rarely basal and cauline (P. retrorsus), opposite, leathery or not, glabrous, glabrate, pubescent, scabrous, puberulent, or retrorsely hairy, not glaucous;
basal and proximal cauline petiolate;
cauline petiolate or sessile, blade obovate, spatulate, oblanceolate, lanceolate, elliptic, or linear, margins entire.
continuous or interrupted, cylindric or secund, axis retrorsely hairy, glandular-pubescent, or puberulent and glandular-pubescent, rarely glabrous, cymes 1 or 2 per node;
peduncles and pedicels spreading to ascending or erect.
calyx tube 0.2–1 mm (1.5–2 mm in P. retrorsus), lobes: margins entire or erose, ± scarious or herbaceous, glandular-pubescent or retrorsely hairy, rarely glabrate;
corolla lavender, blue, violet, or purple, rarely scarlet, bilaterally symmetric, bilabiate, not personate, funnelform, tubular-funnelform, salverform, ventricose-ampliate, or ampliate, glandular-pubescent externally, hairy internally abaxially, rarely glabrous, throat slightly to abruptly inflated, not constricted at orifice, 2-ridged abaxially;
stamens included to exserted, filaments glabrous, rarely sparsely glandular-puberulent proximally, pollen sacs opposite, rarely divergent, navicular to subexplanate or explanate, dehiscing completely, connective splitting, sides glabrous, sutures papillate or smooth;
staminode included to exserted, ± flattened distally, 0.1–0.5 mm diam., tip straight to recurved, distal (20–)50–100% hairy, hairs to 0.7–1.3 mm;
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.
dark brown to black, angled to rounded, 1.1–2.1 mm.
angled or rounded, rarely angled-elongate, reniform, or disciform, wings absent.
Penstemon sect. Caespitosi
Penstemon subg. Penstemon
Species 11 (11 in the flora).
Most species of sect. Caespitosi formed a clade in the molecular study by A. D. Wolfe et al. (2006); placement of the clade within subg. Penstemon is not clear.
(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 salverform, scarlet (throats sometimes yellow or yellow- or orange-spotted). | P. pinifolius |
1. Corollas tubular-funnelform, funnelform, ampliate, or ventricose-ampliate, lavender, blue, violet, or purple. | → 2 |
2. Leaves glabrous or retrorsely hairy, hairs appressed, white, scalelike. | → 3 |
3. Stems prostrate, spreading, or ascending; cauline leaves 1–5 pairs. | → 4 |
4. Leaves densely retrorsely hairy, hairs appressed, white, scalelike; pollen sacs 0.8–1.2(–1.4) mm; Arizona, California, Nevada, Utah. | P. thompsoniae |
4. Leaves glabrous or sparsely hairy, hairs appressed, white, scalelike abaxially, ± densely hairy, hairs appressed, white, scalelike adaxially; pollen sacs 0.6–0.8 mm; Utah. | P. xylus |
3. Stems ascending to erect; cauline leaves 6–30 pairs. | → 5 |
5. Leaves glabrous, rarely sparsely retrorsely hairy, hairs white, scalelike abaxially, densely puberulent, hairs white, scalelike adaxially; corollas 9–14 mm; pollen sacs 0.5–0.8 mm; Arizona. | P. discolor |
5. Leaves sparsely to densely retrorsely hairy, hairs appressed, white, scalelike; corollas 14–20 mm; pollen sacs 0.9–1.4 mm; Arizona, California, New Mexico. | → 6 |
6. Corollas tubular-funnelform, 14–18 mm, purple to violet; California. | P. californicus |
6. Corollas ventricose-ampliate, 16–20 mm, blue to lavender; Arizona, New Mexico. | P. linarioides |
2. Leaves glabrous, glabrate, or hairy, hairs pointed. | → 7 |
7. Calyx tubes 1.5–2 mm; proximal bracts oblanceolate. | P. retrorsus |
7. Calyx tubes 0.2–1 mm; proximal bracts oblanceolate to linear. | → 8 |
8. Calyx lobes herbaceous- or narrowly scarious-margined. | → 9 |
9. Stems and leaves not cinereous; leaf blades obovate to spatulate, oblanceolate, or linear; Arizona, Colorado, Utah, Wyoming. | P. caespitosus |
9. Stems and leaves cinereous; leaf blades linear; Colorado. | P. teucrioides |
8. Calyx lobes broadly scarious-margined. | → 10 |
10. Corollas ventricose-ampliate; calyx lobe apices acute to acuminate. | P. linarioides |
10. Corollas funnelform; calyx lobe apices acuminate to caudate. | → 11 |
11. Leaf blades linear, rarely oblanceolate; stems ascending to erect; corollas glabrous or sparsely white-villous internally abaxially; Utah. | P. abietinus |
11. Leaf blades elliptic to obovate, oblanceolate, or linear; stems prostrate, decumbent, ascending, or erect; corollas sparsely to densely yellow-lanate or yellow-pilose internally abaxially; Colorado, New Mexico, Utah. | P. crandallii |
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 |
