Herbs or subshrubs. Stems decumbent to ascending or erect, 15–90 cm, retrorsely hairy, hairs pointed, not glaucous. Leaves cauline, opposite, puberulent or retrorsely hairy, hairs pointed, sometimes glabrate, not glaucous; cauline 4–8 pairs, sessile or proximals short-petiolate, 13–85(–110) × 2–22 mm, blade oblanceolate to lanceolate or linear, base tapered to truncate, margins entire, apex acute. Thyrses interrupted, cylindric, 10–30(–43) cm, axis glandular-pubescent, verticillasters 6–12, cymes 1–5-flowered, 2 per node; proximal bracts lanceolate, rarely linear, 9–40 × 2–10 mm; peduncles and pedicels spreading to ascending, glandular-pubescent. Flowers: calyx lobes ovate to lanceolate, 4–11 × 1–2.8 mm, glandular-pubescent; corolla violet to blue or purple, with or without violet nectar guides, funnelform to ampliate, 21–35 mm, glandular-pubescent externally, glabrous internally, tube 6–9 mm, throat gradually inflated, 8–10 mm diam., 2-ridged abaxially; stamens included or longer pair reaching orifice, filaments glabrous, pollen sacs parallel, 1.8–2.8 mm, distal 1/5–1/3 indehiscent, sides pubescent to lanate, hairs white, to 1 mm near filament attachment, sutures denticulate, teeth to 0.3 mm; staminode 17–19 mm, included or reaching orifice, 0.5–0.6 mm diam., glabrous; style 16–22 mm. Capsules 7–9 × 4–6 mm.
Varieties 3 (3 in the flora).
Penstemon laetus occurs from the Cascade Range of south-central Oregon south through the Sierra Nevada of California to the Western Transverse Ranges of southwestern California. The species comprises three partially sympatric varieties.
The Karuk tribe of northwestern California use an infusion of Penstemon laetus as a psychological aid (D. E. Moerman 1998).
|1||Calyx lobes lanceolate, 7–11 × 1–2 mm.||Penstemon laetus var. leptosepalus|
|1||Calyx lobes ovate to lanceolate, 4–8.5 × 1–2.8 mm.||> 2|
|2||Anthers ovate to elliptic in outline, pollen sacs 1.8–2.3 mm.||Penstemon laetus var. laetus|
|2||Anthers sagittate in outline, pollen sacs 2.1–2.8 mm.||Penstemon laetus var. sagittatus|