J. Acad. Nat. Sci. Philadelphia 7: 46. 1834. (as Pentstemon pumilum)
Stems decumbent, ascending, or erect, 3–12 cm, retrorsely hairy. Leaves basal and cauline or mostly basal, not leathery, retrorsely hairy; basal and proximal cauline short-petiolate or sessile, 7–35(–50) × 1–4 mm, blade oblanceolate to linear, base tapered, margins entire, apex obtuse to acute; cauline 1–3 pairs, sessile, 12–30 × 1–4 mm, blade oblanceolate to oblong or linear, usually arcuate, base tapered, margins entire, apex acute. Thyrses interrupted to compact, cylindric, 1–6 cm, axis retrorsely hairy, verticillasters 1–6, cymes 1- or 2-flowered, 1 or 2 per node; proximal bracts oblanceolate to lanceolate, 7–30 × 1–3 mm; peduncles and pedicels retrorsely hairy and sparsely glandular-pubescent. Flowers: calyx lobes lanceolate, 4.5–7 × 1.5–2 mm, puberulent and glandular-pubescent; corolla blue to violet, with reddish purple nectar guides, tubular-funnelform, 15–20(–23) mm, glabrous or sparsely white-lanate internally abaxially, tube 4–6 mm, throat gradually inflated, not constricted at orifice, 6–8 mm diam., rounded abaxially; stamens included, pollen sacs opposite, navicular, 0.9–1.2 mm, dehiscing completely, sutures papillate; staminode 9–12 mm, included, 0.5–0.6 mm diam., tip recurved, distal 6–8 mm sparsely pilose, hairs yellow, to 0.5 mm; style 9–11 mm. Capsules 4–7 × 3.5–5.5 mm.
Phenology: Flowering May–Jun.
Habitat: Gravelly soils, limestone, sagebrush shrublands.
Elevation: 1400–2100 m.
Penstemon pumilus is known from east-central Idaho in Butte, Clark, Custer, and Lemhi counties. The arcuate cauline leaves with acute apices and tufted basal leaves reliably distinguish this species from the other diminutive members of sect. Cristati.