Bull. Torrey Bot. Club 28: 28. 1901.
Herbs. Stems ascending to erect, (20–) 35–100 cm, glabrous or sparsely to densely puberulent, sometimes also sparsely glandular-pubescent, especially distally, not glaucous. Leaves basal and cauline, ± leathery or not, glabrous or puberulent to pubescent, especially along midveins; basal and proximal cauline (25–) 35–190 × (5–) 12–55 mm, blade triangular to ovate or lanceolate, base tapered, rarely truncate, margins ± serrate or dentate, apex acute, rarely obtuse; cauline 2–5 pairs, short-petiolate or sessile, 35–90 × (8–) 15–50 mm, blade ovate to oblong or lanceolate, base tapered to clasping or cordate-clasping, margins serrate to dentate, apex obtuse to acute. Thyrses interrupted, cylindric to conic, (5–) 8–30 cm, axis sparsely to moderately glandular-pubescent, verticillasters 3–7, cymes 3–11-flowered, 2 per node; proximal bracts ovate to lanceolate, (8–) 18–75 × (5–) 8–35 mm, margins ± serrate to dentate; peduncles and pedicels spreading to ascending, ± glandular-pubescent. Flowers: calyx lobes ovate, 2.4–5.5 × 0.9–1.8 mm, margins broadly scarious, glandular-pubescent; corolla blue to violet or light blue, with reddish purple nectar guides, funnelform, 13–23 mm, glandular-pubescent externally, sparsely white or yellow-villous internally abaxially, tube 4–8 mm, throat gradually inflated, 4–9 mm diam., 2-ridged abaxially; stamens included, pollen-sacs opposite, navicular to subexplanate, 0.8–1 mm, dehiscing completely, connective splitting, sides glabrous, sutures smooth or ± papillate; staminode 8–11 mm, reaching orifice, 0.2–0.3 mm diam., tip straight to recurved, distal 1–5 mm pilose to villous, hairs yellow, to 1.2 mm; style 9–13 mm. Capsules 4–6.5 × 3–4 mm, glabrous. 2n = 16, 32.
Phenology: Flowering May–Aug.
Habitat: Rocky or gravelly slopes in forests and woodlands, roadcuts.
Elevation: 300–2300 m.
Idaho, Mont., Oreg., Wash.
Penstemon wilcoxii hybridizes with P. albertinus in areas of sympatry in east-central Idaho and west-central Montana (D. D. Keck 1945; A. Cronquist 1959; D. V. Clark 1971). Putative hybrids and/or introgressants exhibit varying degrees of morphologic intermediacy between the parent species. Many herbarium specimens are difficult to determine with confidence.
"/4+timescorollathroat" is not declared as a valid unit of measurement for this property.