Annuals (4–)6–35 cm. Stems erect to ascending. Leaf blades narrowly oblong to lanceolate, margins subentire. Inflorescences glabrous or finely glandular to scaly-hairy; nodes 1–6(–8)-flowered; flowers not crowded proximally, sometimes crowded distally; distalmost bracts linear, 5–6(+) mm. Pedicels ascending to reflexed, proximals usually longer than calyx, visible. Flowers: caly× lobes ± deltate, equal to capsule, ape× acuminate; corolla bluish, banner pale at center, 8–15 mm, keel glabrous; banner length 0.8–1 times wings, lobe base without folds; banner lobes and wings widely obovate, usually 2–6 mm wide; throat strongly angled to tube, longer than diam., pouch prominent, angular; stamens: filaments glabrous, basal spur 0. Seeds (3 or)4, oblong, 2–2.5 mm, margins thickened, inrolled. 2n = 14, 28, 42.
Phenology: Flowering (Mar–)May–Jul.
Habitat: Gravelly or grassy margins of coniferous or open oak woodlands, moss-covered rock outcrops, other open areas.
Elevation: 0–1800 m.
B.C., Calif., Oreg., Wash.
Collinsia grandiflora occurs mostly in the coastal ranges. The distinction between C. grandiflora and C. parviflora is usually clear in California where corolla lobe shape and size are mostly well correlated. The distinction is much less clear in British Columbia, Oregon, and Washington.
An alternative to the treatment here would be to follow F. R. Ganders and G. R. Krause (1986), who suggested that Collinsia grandiflora and C. parviflora be treated as one species with two intergrading varieties.