Notul. Nat. Acad. Nat. Sci. Philadelphia 71: 13. 1941.
Herbs. Stems ascending to erect, 20–80 cm, glabrous or retrorsely hairy, rarely sparsely glandular-pubescent, not glaucous. Leaves basal and cauline, not leathery, glabrous or puberulent (especially on petiole and along major veins and margins); basal and proximal cauline 30–120 (–160) × 4–32 mm, blade ovate to elliptic, rarely spatulate, base tapered, margins serrate to serrulate or entire, apex obtuse to acute, rarely rounded; cauline 2–6 pairs, sessile, 20–75 × 5–27 mm, blade lanceolate to oblong, base truncate to clasping, margins serrate to serrulate, sometimes entire, apex obtuse to acute or acuminate. Thyrses interrupted, cylindric to narrowly conic, 18–37 cm, axis moderately to densely glandular-pubescent, verticillasters 5–11, cymes 3–11-flowered, 2 per node; proximal bracts ovate to lanceolate, 25–60 × 9–30 mm, margins serrate to serrulate, sometimes entire; peduncles and pedicels ascending to erect, glandular-pubescent. Flowers: calyx lobes ovate to lanceolate, 3–5 × 1.4–2.5 mm, margins narrowly to broadly scarious, glandular-pubescent to densely glandular-pubescent; corolla blue to violet or purple, with reddish purple nectar guides, funnelform, 12–18 mm, glandular-pubescent externally, moderately white-lanate internally abaxially, tube 4–5 mm, throat slightly inflated, 3–6 mm diam., 2-ridged abaxially; stamens included, pollen-sacs opposite, navicular to subexplanate, 0.7–1.1 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 8–10 mm, included, 0.3–0.5 mm diam., tip recurved, distal 2–3 mm sparsely to moderately pilose, hairs yellow or yellow-orange, to 1.5 mm; style 8–11 mm. Capsules 4–5 × 3–4 mm, glabrous. 2n = 32.
Phenology: Flowering May–Jul.
Habitat: Open slopes in pine forests and pine-oak woodlands.
Elevation: 30–1800 m.
Penstemon subserratus occurs along the eastern flank of the Cascade Range.
"/4+timescorollathroat" is not declared as a valid unit of measurement for this property.