Madroño 14: 156, fig. 2. 1958.
Stems prostrate to ascending, to 1 cm, scabrous or puberulent. Leaves essentially basal, not leathery, scabrous; basal and proximal cauline sessile, 15–25 (–35) × 1.5–2.6 (–4.5) mm, blade oblanceolate to linear, base tapered, margins entire or obscurely dentate distally, apex obtuse to acute. Thyrses essentially absent, 0.1–0.6 cm, axis puberulent, verticillasters 1 or 2, cymes 1 (–3) -flowered, 1 (or 2) per node; proximal bracts oblanceolate to linear, 8–20 × 1–3 mm; peduncles and pedicels glandular-pubescent and scabrous. Flowers: calyx lobes lanceolate, 5–6.5 × 1–1.8 mm, glandular-pubescent and scabrous; corolla lavender to bluish lavender, without nectar guides, funnelform, 14–18 mm, yellowish or whitish villous internally abaxially, tube 5–6 mm, throat gradually inflated, not constricted at orifice, 4.5–6 mm diam., slightly 2-ridged abaxially; stamens: longer pair reaching orifice, pollen-sacs widely divergent to opposite, navicular, 0.8–1.3 mm, dehiscing completely, sutures papillate; staminode 8–11 mm, prominently exserted, 0.5–0.8 mm diam., tip straight to recurved, distal 5–7 mm densely pubescent, hairs orange, to 1 mm; style 9–12 mm. Capsules 3.5–5 × 3–4 mm.
Phenology: Flowering May–Jul.
Habitat: Semi-barren ledges and ridges, hilltops, pinyon-juniper woodlands, sagebrush shrublands.
Elevation: 1800–2200 m.
Colo., Utah, Wyo.
Penstemon yampaënsis is known from Moffat County, Colorado, Daggett and Uintah counties, Utah, and Sweetwater County, Wyoming. The species appears to be closely related to P. acaulis. Seed release appears to occur as the walls of the capsules deteriorate, rather than through an apical opening as in other Penstemon species. This type of dehiscence also occurs in P. acaulis.
"/4+timescorollathroat" is not declared as a valid unit of measurement for this property.