Herbs or subshrubs. Stems glabrous, puberulent, or retrorsely hairy, rarely glandular-pubescent distally or wholly or retrorsely hairy, glaucous or not. Leaves basal and cauline, basals sometimes few, or cauline, opposite, sometimes alternate, rarely whorled or subalternate, leathery, rarely not (P. papillatus, P. platyphyllus), glabrous, glabrate, puberulent, retrorsely hairy, canescent, pilose, hirsute, or glandular-pubescent, glaucous or not; basal and proximal cauline petiolate; cauline sessile, petiolate, or short-petiolate, blade obovate, ovate, spatulate, oblanceolate, lanceolate, elliptic, oblong, or linear, margins entire or toothed, rarely laciniate-pinnatifid. Thyrses interrupted or continuous, cylindric, sometimes secund, axis glabrous, glandular-pubescent, puberulent, or retrorsely hairy, cymes 1 or 2 per node; peduncles and pedicels spreading to ascending or erect, rarely appressed. Flowers: calyx lobes: margins entire or erose, rarely lacerate (P. serrulatus), narrowly scarious or scarious, sometimes herbaceous, rarely broadly scarious (P. serrulatus), glabrous or glandular-pubescent, rarely scabrous, puberulent, pubescent, or ciliolate; corolla lavender to blue, violet, purple, reddish purple, or pinkish, bilaterally symmetric, ± bilabiate, not personate, funnelform, ventricose, ampliate, or ventricose-ampliate, glabrous or glandular-pubescent externally, glabrous or hairy internally abaxially, throat slightly to gradually inflated, not constricted at orifice, rounded to 2-ridged abaxially; stamens included or longer pair reaching orifice or exserted, filaments glabrous, rarely hairy distally, pollen sacs parallel, rarely divergent, saccate, dehiscing incompletely, distal 1/5–2/3 indehiscent, connective splitting, sides glabrous or hairy, sutures denticulate, teeth to 0.3 mm; staminode included to exserted, flattened distally, 0.2–1 mm diam., tip straight, glabrous or distal 5–50(–60)% hairy, hairs to 2.5 mm; style glabrous. Capsules glabrous. Seeds tan, gray, or brown, angled, rarely patelliform, 0.5–3.4 mm.

Distribution

w North America.

Discussion

Species 27 (27 in the flora).

D. D. Keck (1932) included most species of Penstemon with saccate anthers in subg. Saccanthera, sect. Saccanthera. Most members of sect. Saccanthera formed a clade nested in subg. Penstemon in the molecular study by A. D. Wolfe et al. (2006).

Selected References

Keck, D. D. 1932. Studies in Penstemon. A systematic treatment of section Saccanthera. Univ. Calif. Publ. Bot. 16: 367–426.

Lower Taxa

Penstemon azureus, Penstemon caesius, Penstemon cusickii, Penstemon diphyllus, Penstemon filiformis, Penstemon floribundus, Penstemon glandulosus, Penstemon gracilentus, Penstemon heterophyllus, Penstemon kingii, Penstemon laetus, Penstemon leonardii, Penstemon neotericus, Penstemon papillatus, Penstemon parvulus, Penstemon platyphyllus, Penstemon pudicus, Penstemon purpusii, Penstemon rhizomatosus, Penstemon richardsonii, Penstemon roezlii, Penstemon scapoides, Penstemon sepalulus, Penstemon serrulatus, Penstemon tiehmii, Penstemon triphyllus, Penstemon venustus

Key

1	Leaf blade margins serrate, dentate, laciniate-dentate, or laciniate-pinnatifid.	> 2
2	Stems viscid glandular-pubescent.	Penstemon glandulosus
2	Stems glabrous or retrorsely hairy.	> 3
3	Calyx lobes glabrous, glabrate, or sparsely puberulent, margins sometimes ciliate.	> 4
4	Styles 10–16 mm; filaments glabrous.	Penstemon serrulatus
4	Styles 18–25 mm; filaments white-lanate distally, rarely glabrous.	Penstemon venustus
3	Calyx lobes glandular-pubescent.	> 5
5	Corollas ventricose-ampliate, 15–32 mm; pollen sacs 1.3–2 mm; styles 11–23 mm.	Penstemon richardsonii
5	Corollas funnelform, 13–19 mm; pollen sacs 0.9–1.3 mm; styles 8–12 mm.	> 6
6	Leaves opposite, sometimes alternate; staminodes: distal 1–4 mm sparsely to moderately lanate, hairs white or yellowish, to 1.5 mm.	Penstemon diphyllus
6	Leaves whorled, sometimes alternate; staminodes: distal 6–7 mm moderately to densely lanate, hairs yellow, to 2.5 mm.	Penstemon triphyllus
1	Leaf blade margins entire or subentire.	> 7
7	Stems viscid glandular-pubescent.	Penstemon glandulosus
7	Stems glabrous, retrorsely hairy, puberulent, or pilose.	> 8
8	Staminodes hairy.	> 9
9	Stems retrorsely hairy, hairs appressed, ± scalelike.	Penstemon tiehmii
9	Stems glabrous, retrorsely hairy, or puberulent, sometimes glabrate or hirsute, hairs pointed.	> 10
10	Thyrse axes glabrous or retrorsely hairy; corollas glabrous externally or lobe margins sometimes densely white-ciliate.	> 11
11	Corollas 14–20 mm, glabrous externally; styles 11–14 mm.	Penstemon parvulus
11	Corollas 24–38 mm, glabrous externally except lobe margins densely white-ciliate; styles 18–25 mm.	Penstemon venustus
10	Thyrse axes glandular-pubescent; corollas glandular-pubescent externally.	> 12
12	Leaves hirsute.	Penstemon scapoides
12	Leaves glabrous, retrorsely hairy, or puberulent, sometimes glabrate.	> 13
13	Leaves whorled, sometimes alternate, cauline blades linear, sometimes lanceolate.	Penstemon triphyllus
13	Leaves opposite, cauline blades spatulate, oblanceolate, oblong, elliptic, or lanceolate.	> 14
14	Corollas 15–20(–24) mm; styles 12–15 mm.	Penstemon gracilentus
14	Corollas 24–35 mm; styles 22–30 mm.	> 15
15	Stems retrorsely hairy or puberulent; pollen sacs: distal 1/3 indehiscent.	Penstemon papillatus
15	Stems glabrous proximally, sparsely glandular-pubescent distally; pollen sacs: distal 1/2–2/3 indehiscent.	Penstemon pudicus
8	Staminodes glabrous.	> 16
16	Corollas glabrous externally.	> 17
17	Stems puberulent or retrorsely hairy, at least proximally.	> 18
18	Styles 11–18 mm; corollas 14–26 mm.	> 19
19	Pedicels puberulent or retrorsely hairy.	Penstemon cusickii
19	Pedicels glabrous or papillate distally.	Penstemon leonardii
18	Styles 18–27 mm; corollas (20–)22–38 mm.	> 20
20	Pollen sacs 2.2–3 mm; calyx lobes obovate to oblanceolate or ovate to lanceolate, glabrous or puberulent; staminodes included; California.	Penstemon heterophyllus
20	Pollen sacs 1.5–1.9(–2.1) mm; calyx lobes lanceolate, glabrous; staminodes reaching orifice or exserted; Utah.	Penstemon platyphyllus
17	Stems glabrous.	> 21
21	Pollen sacs: distal 1/2–2/3 indehiscent, sides glabrous; Nevada, Utah.	> 22
22	Cauline leaf pairs 2–6; pollen sacs 2.4–2.8 mm; calyx lobes (4–)5–6.3 mm; Nevada.	Penstemon floribundus
22	Cauline leaf pairs 6–14; pollen sacs 1.5–2 mm; calyx lobes 1.8–3.2 mm; Utah.	Penstemon sepalulus
21	Pollen sacs: distal 1/3–1/2 indehiscent, sides hispidulous, pubescent, pilose, or lanate near filament attachments; California, Oregon.	> 23
23	Corollas 14–20 mm, ventricose; pollen sacs 1.4–1.8 mm; styles 11–14 mm.	Penstemon parvulus
23	Corollas 18–38 mm, ventricose, ventricose-ampliate, or funnelform; pollen sacs 1.8–3.5 mm; styles 16–27 mm.	> 24
24	Leaves glabrous, glaucous; thyrses secund, axes glabrous; proximal bracts ovate to lanceolate.	Penstemon azureus
24	Leaves glabrous or retrorsely hairy, rarely glaucous; thyrses cylindric, axes glabrous or retrorsely hairy; proximal bracts lanceolate to linear.	Penstemon heterophyllus
16	Corollas glandular-pubescent externally.	> 25
25	Cauline leaves 0.5–1(–2) mm wide, blades linear; proximal bracts linear.	Penstemon filiformis
25	Cauline leaves (1–)2–24 mm wide, blades ovate to obovate, spatulate, oblanceolate, lanceolate, or linear; proximal bracts ovate to oblanceolate or lanceolate, rarely linear.	> 26
26	Leaves canescent to pilose.	Penstemon purpusii
26	Leaves glabrous or retrorsely hairy, sometimes glabrate or puberulent.	> 27
27	Stems retrorsely hairy, hairs appressed, scalelike.	> 28
28	Cauline leaves 3–7 mm wide, blades oblanceolate to lanceolate, proximals sometimes spatulate; pollen sacs 0.9–1.2 mm.	Penstemon rhizomatosus
28	Cauline leaves 7–24 mm wide, blades ovate to spatulate or lanceolate; pollen sacs 1.1–1.6 mm.	Penstemon tiehmii
27	Stems glabrous, retrorsely hairy, or ± puberulent, hairs pointed.	> 29
29	Pollen sacs 1–1.5(–1.8) mm, sides glabrous.	> 30
30	Leaves glabrous, usually glaucous; California.	Penstemon caesius
30	Leaves retrorsely hairy, not glaucous; Nevada, Oregon.	Penstemon kingii
29	Pollen sacs 1.5–3.2 mm, sides hispidulous, pubescent, or pilose to lanate.	> 31
31	Stems glabrous, sometimes ± puberulent; leaves glabrous, sometimes proximals puberulent, glaucous; pollen sacs 2.4–3.2 mm.	Penstemon neotericus
31	Stems retrorsely hairy; leaves puberulent or retrorsely hairy, sometimes glabrate, not glaucous; pollen sacs 1.5–2.8 mm.	> 32
32	Corollas 21–35 mm; pollen sacs 1.8–2.8 mm.	Penstemon laetus
32	Corollas 15–25 mm; pollen sacs 1.5–2 mm.	Penstemon roezlii