Proc. Amer. Acad. Arts 6: 69. 1862. (as Pentstemon)
Herbs. Stems decumbent to erect, (2–)5–30(–65) cm, retrorsely hairy, not glaucous. Leaves basal and cauline, not leathery, glabrous or retrorsely hairy; basal and proximal cauline (8–)15–105 × 2–22(–32) mm, blade obovate to ovate or oblanceolate, base tapered, margins entire, sometimes serrulate or serrate, apex obtuse to acute; cauline (1 or)2–4 pairs, sessile or proximals short-petiolate, 10–35(–45) × 1–11 mm, blade obovate to oblanceolate or lanceolate, base tapered to clasping, margins entire, rarely ± serrate, apex obtuse to acute. Thyrses interrupted, cylindric to ± secund, (1–)3–20(–39) cm, axis moderately glandular-pubescent, verticillasters (1–)3–9(–11), cymes (1 or)2–6(–11)-flowered, 2 per node; proximal bracts lanceolate, rarely ovate, 6–34(–48) × 1–11 mm, margins entire; peduncles and pedicels ascending to erect, glandular-pubescent and, usually, retrorsely hairy. Flowers: calyx lobes ovate to lanceolate, 2.8–5(–6) × 1–1.9 mm, margins entire or erose, apex acute, glandular-pubescent; corolla blue to purple or violet, with reddish violet nectar guides, bilabiate, not personate, tubular-funnelform, (7–)8–19 mm, glandular-pubescent externally, sparsely to moderately white- or yellow-lanate internally abaxially, tube 2–5 mm, throat slightly inflated, (3–)4.5–6 mm diam., 2-ridged abaxially; stamens included, pollen sacs opposite, navicular, 0.5–0.8 mm, dehiscing completely, connective splitting, sides glabrous, sutures smooth or papillate; staminode (3–)7–9 mm, included, 0.1–0.3 mm diam., tip slightly recurved, distal 1–4 mm sparsely to densely pilose, hairs yellow or golden yellow, to 0.7 mm (medial hairs sparser and shorter); style 6–12 mm. Capsules 4–6 × 2.5–3.5 mm, glabrous.
Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
Varieties 3 (3 in the flora).
Penstemon humilis is widespread and extremely variable throughout its range in the western United States. Except for two fairly distinct elements in Utah, most variation in the species is contained in the widespread var. humilis. D. D. Keck (1945) and N. H. Holmgren (1984) summarized the ranges and morphologic tendencies of some of the more distinctive phases.
|1||Cauline leaf blade margins ± serrate; basal leaves (4–)7–22(–32) mm wide; sw Utah.||Penstemon humilis var. obtusifolius|
|1||Cauline leaf blade margins entire, rarely ± serrate distally; basal leaves 2–20 mm wide; California, nw Colorado, s Idaho, sw Montana, Nevada, e Oregon, Utah, Washington, w Wyoming.||> 2|
|2||Basal leaves puberulent or retrorsely hairy; corollas (7–)12–19 mm; California, nw Colorado, s Idaho, sw Montana, Nevada, e Oregon, Utah, Washington, w Wyoming.||Penstemon humilis var. humilis|
|2||Basal leaves glabrous, sometimes ± puberulent, especially along midveins and margins; corollas 10–13 mm; nc Utah.||Penstemon humilis var. brevifolius|