Bot. Gaz. 56: 70. 1913. (as Pentstemon)
Herbs. Stems erect, 12–50 cm, retrorsely hairy proximally, becoming glandular-pubescent distally, not glaucous. Leaves basal and cauline, not leathery, glabrous or retrorsely hairy abaxially along midvein and glabrous adaxially, ± glaucescent; basal and proximal cauline 13–55 × 4–8(–12) mm, blade spatulate to oblanceolate or elliptic, base tapered, margins entire, apex rounded to acute; cauline 2–5(or 6) pairs, sessile, 5–40(–52) × 0.3–5 mm, blade linear, base tapered, margins entire, apex acuminate. Thyrses interrupted, secund, 1–14 cm, axis glandular-pubescent, verticillasters (1–)3 or 4(or 5), cymes 1–3-flowered, 1(or 2) per node; proximal bracts linear, 3–15 × 0.3–1.4 mm; peduncles and pedicels erect, sometimes ascending, glandular-pubescent. Flowers: calyx lobes ovate to lanceolate, 3.8–7.5 × 1.5–2.6 mm, glabrescent or glandular-pubescent; corolla violet to blue or purple, with violet nectar guides, tubular-funnelform, 17–25 mm, glandular-pubescent externally, densely golden-villous internally abaxially, tube 4–7 mm, throat slightly inflated, 5–7 mm diam., prominently 2-ridged abaxially; stamens included, pollen sacs divergent to opposite, navicular, 1–1.3 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 10–13 mm, included, 0.2–0.3 mm diam., tip straight to recurved, distal 7–11 mm densely pilose, hairs golden, to 1.5 mm; style 12–17 mm. Capsules 6–9 × 4–5 mm, glabrous.
Phenology: Flowering Jun–Aug.
Habitat: Rocky hillsides, open coniferous forests, montane grasslands.
Elevation: 2500–3000 m.
Populations of Penstemon griffinii are documented in Chaffee, Conejos, Fremont, Mineral, Park, Rio Grande, and Saguache counties, Colorado, and Rio Arriba and Taos counties, New Mexico. Penstemon griffinii can be confused with narrow-leaved plants of P. degeneri, but the pubescence on the internal abaxial surfaces of the corollas of P. griffinii is consistently golden-lanate and extends from the abaxial limbs 5–8 mm into the throats of the corollas. In P. degeneri, the internal abaxial surfaces of the corollas are white- or yellow-lanate, sometimes sparsely so, and the indument barely extends into the throats of the corollas.