Stems ascending to erect, 5–20(–30) cm, retrorsely hairy. Leaves basal and cauline, not leathery, retrorsely hairy; basal and proximal cauline petiolate, 12–55(–75) × 4–12 mm, blade elliptic to spatulate, base tapered, margins entire or obscurely and remotely serrate, apex rounded to obtuse or acute; cauline 2–5 pairs, short-petiolate or sessile, 19–65 × 2–8 mm, blade lanceolate to oblanceolate, base truncate to tapered, margins entire or remotely serrate, apex obtuse to acute. Thyrses continuous, cylindric, 2–10 cm, axis densely glandular-pubescent, verticillasters 3–8, cymes 3–5-flowered, 2 per node; proximal bracts lanceolate, 18–70 × 3–8 mm; peduncles and pedicels densely glandular-pubescent. Flowers: calyx lobes lanceolate, 4.5–7 × 1.1–1.8 mm, glandular-pubescent; corolla lavender to bluish lavender or violet, with reddish violet nectar guides, ventricose, 10–14 mm, sparsely to densely white- or yellowish lanate internally abaxially, tube 4–6 mm, throat abruptly inflated, ± constricted at orifice, 4–5 mm diam., rounded abaxially; stamens included, pollen sacs opposite, explanate, 0.6–0.9 mm, dehiscing completely, sutures smooth; staminode 9–10 mm, prominently exserted, 0.2 mm diam., tip coiled, distal 5–6 mm densely pubescent, hairs orange or orangish yellow, to 1.2 mm; style 7–9 mm. Capsules 3–6 × 3–5 mm.
Phenology: Flowering May–Jun.
Habitat: Alluvial gravels, calcareous silts, sagebrush shrublands, pinyon-juniper woodlands.
Elevation: 1500–2500 m.
Penstemon barnebyi is known from Mono County, California, and Esmeralda, Lincoln, Mineral, Nye, and White Pine counties, Nevada.