Flora of North America species comparison

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Penstemon sect. Caespitosi
Habit Subshrubs, usually cespitose.
Stems

retrorsely hairy, rarely glabrous, not glaucous.
Leaves

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.
Thyrses

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.
Flowers

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.
Capsules

glabrous.
Seeds

dark brown to black, angled to rounded, 1.1–2.1 mm.

Penstemon sect. Caespitosi
Distribution
w United States; nw Mexico
Discussion

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.)
Key
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
Source FNA vol. 17, p. 98.
Parent taxa Plantaginaceae > Penstemon > subg. Penstemon
Subordinate taxa
P. abietinus, P. caespitosus, P. californicus, P. crandallii, P. discolor, P. linarioides, P. pinifolius, P. retrorsus, P. teucrioides, P. thompsoniae, P. xylus
Synonyms P.
Name authority (Rydberg) Pennell: Contr. U.S. Natl. Herb. 20: 327, 334. (1920)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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