Contr. Bot. Lab. Morris Arbor. Univ. Pennsylvania 3: 193. 1908.
Herbs or subshrubs. Stems ascending to erect, (10–) 15–40 cm, glabrous, glaucous. Leaves cauline, opposite, glabrous, sometimes proximals retrorsely hairy, hairs pointed, usually glaucous; cauline 3–8 pairs, short-petiolate or sessile, (6–) 10–50 × (2–) 4–9 mm, blade oblanceolate to oblong or lanceolate, base tapered to truncate or cordate, margins entire, apex obtuse to acute. Thyrses continuous, cylindric, 4–11 cm, axis glabrous, verticillasters 4 or 5, cymes 2–4-flowered, 2 per node; proximal bracts ovate to oblong or lanceolate, 4–34 × 2–8 mm; peduncles and pedicels ascending to erect, glabrous. Flowers: calyx lobes obovate to ovate or lanceolate, 3–5 × 1.5–2.5 mm, glabrous; corolla blue to violet or purple, without nectar guides, ventricose, 14–20 mm, glabrous externally, glabrous internally, tube 4–5 mm, throat gradually inflated, 5–7 mm diam., 2-ridged abaxially; stamens included, filaments glabrous, pollen-sacs parallel, 1.4–1.8 mm, distal 1/3–1/2 indehiscent, sides hispidulous, hairs white, to 0.3 mm near filament attachment, sometimes sparsely so, sutures denticulate, teeth to 0.2 mm; staminode 10–12 mm, included, 0.4–0.6 mm diam., glabrous or distal 0.5 mm sparsely pubescent, hairs whitish, to 0.2 mm; style 11–14 mm. Capsules 5–8 × 3.5–5 mm. 2n = 32.
Phenology: Flowering Jun–Aug.
Habitat: Rocky, open foothills and montane forests.
Elevation: 500–2500(–3000) m.
Penstemon parvulus occurs in the Klamath Ranges of northern California and southwestern Oregon and in the southern High Sierra Nevada of south-central California.
"/4+timescorollathroat" is not declared as a valid unit of measurement for this property.