Stems ascending to erect, (9–)20–60 cm, glabrous or ± scabrous, especially distally. Leaves basal and cauline, glabrous, sometimes scabrous; basal and proximal cauline (14–)30–95 × 4–15(–24) mm, blade oblanceolate to elliptic, base tapered, apex obtuse to acute or mucronate; cauline (2 or)3–6(or 7) pairs, sessile, 18–60(–85) × (4–)8–28 mm, blade ovate to lanceolate, base tapered to cordate-clasping, apex acute to acuminate. Thyrses continuous or interrupted, cylindric, 6–25(–30) cm, axis glabrous, rarely scabrous or glutinous, verticillasters (5–)7–15, cymes (2–)4–8(–12)-flowered; proximal bracts ovate to lanceolate, 14–60 × 9–30 mm, margins entire, apex obtuse to acuminate or caudate; peduncles and pedicels glabrous or scabrous, sometimes also glutinous, peduncles to 4 mm. Flowers: calyx lobes lanceolate, (3.2–)4.5–10 × 1.2–3.2(–3.8) mm, margins entire or erose, herbaceous or narrowly scarious, glabrous or scabrous proximally and, sometimes, along margins, sometimes also glutinous; corolla blue to violet or purple, with reddish purple nectar guides, tubular-funnelform, 11–20 mm, glabrous externally, glabrous internally, tube 5–9 mm, throat gradually inflated, 4–6 mm diam., rounded abaxially; stamens included or longer pair reaching orifice to slightly exserted, pollen sacs opposite, navicular, 0.7–1.3(–1.5) mm, sutures papillate; staminode 6–12 mm, reaching orifice, 0.6–1 mm diam., tip recurved, distal 1.5–3.5 mm densely pilose, hairs golden yellow, to 0.6 mm, hairs on proximal part of staminode mostly along margins; style 8–15 mm. Capsules 7–13 × 4–7 mm.

Distribution

w United States.

Discussion

Varieties 2 (2 in the flora).

Penstemon acuminatus includes the northern var. acuminatus, which has denser thyrses than the southern var. latebracteatus. Herbage of var. acuminatus is usually scabrous; herbage of var. latebracteatus is rarely scabrous.

The Blackfoot tribe of the Central Rocky Mountains use Penstemon acuminatus as an analgesic, antiemetic, and gastrointestinal aid (D. E. Moerman 1998).

Selected References

None.

Lower Taxa

Penstemon acuminatus var. acuminatus, Penstemon acuminatus var. latebracteatus

Key

1	Styles 11–15 mm; corollas 14–20 mm; pollen sacs 0.8–1.3(–1.5) mm; calyx lobes 5–10 mm.	Penstemon acuminatus var. acuminatus
1	Styles 8–11 mm; corollas 11–15 mm; pollen sacs 0.7–1 mm; calyx lobes (3.2–)4.5–7 mm.	Penstemon acuminatus var. latebracteatus