Proc. Amer. Acad. Arts 19: 92. 1883.
Herbs. Stems erect, 14–30 (–45) cm, glabrous, sometimes glaucous. Leaves basal and cauline, opposite, glabrous, usually glaucous; basal and proximal cauline (7–) 15–50 × (4–) 7–20 mm, blade ovate to deltate, base tapered to truncate, margins entire, apex rounded to obtuse; cauline 1 or 2 (or 3) pairs, short-petiolate or sessile, 12–57 × 3–20 mm, blade oblanceolate, base tapered to truncate, margins entire, apex obtuse to acute. Thyrses interrupted, cylindric, 6–17 cm, axis glandular-pubescent, verticillasters 3–5, cymes 1–3-flowered, 2 per node; proximal bracts oblanceolate to lanceolate, 6–28 × 1–6 mm; peduncles and pedicels ascending, glandular-pubescent. Flowers: calyx lobes oblong to lanceolate, 3.5–5 × 1.5–2.1 mm, glandular-pubescent; corolla light purple to lavender, violet, or blue, without nectar guides, ventricose, 17–23 mm, glandular-pubescent externally, glabrous internally, tube 4.5–6 mm, throat slightly inflated, 4.5–7 mm diam., 2-ridged abaxially; stamens included, filaments glabrous, pollen-sacs parallel, 1.1–1.3 mm, distal 1/2 indehiscent, sides glabrous, sutures denticulate, teeth to 0.1 mm; staminode 10–13 mm, included, 0.2–0.3 mm diam., glabrous; style 11–13 mm. Capsules (6–) 8–10 × 4–5.5 mm.
Phenology: Flowering Jun–Aug.
Habitat: Rock slopes, openings in pine forests.
Elevation: 2000–3100 m.
Penstemon caesius is known from the High Sierra Nevada and San Bernardino and San Gabriel mountains in southern California. The species has been documented in Fresno, Inyo, Kern, Los Angeles, San Bernardino, and Tulare counties.
"/4+timescorollathroat" is not declared as a valid unit of measurement for this property.