Gartenflora 1868: 33, plate 568. 1868.
Annuals 5–25 cm. Stems decumbent. Leaf blades lanceolate to ovate, margins crenate, abaxial surface glabrous, adaxial subglabrous or finely gray-hairy. Inflorescences sparsely and finely glandular; whorl 1 per branch; nodes (1–)3–10-flowered; flowers crowded; distalmost bracts ovate, 5–9 mm. Pedicels ascending to spreading, shorter than calyx, not or scarcely visible. Flowers: calyx lobes oblong to ovate, surpassing capsule, ape× rounded; corolla usually whitish, 14–22 mm, wings sparsely and finely glandular, not hairy; banner length 0.1–0.3(–0.4) times wings, lobe base without folds, reflexed portion 1 mm, shorter than basal portion, brownish, not red-banded; stamens: filaments hairy, basal spur 0. Seeds 8–16, oblong to oval, 2–2.5 mm, margins thickened, inrolled. 2n = 14.
Phenology: Flowering Apr–Jun.
Habitat: Coastal sand dunes.
Elevation: 0–20 m.
Collinsia corymbosa is known from Mendocino County. Specimens from other sites identified as C. corymbosa are C. bartsiifolia var. hirsuta. A phylogenetic study using DNA showed evidence of a close relationship between C. corymbosa and C. bartsiifolia (B. G. Baldwin et al. 2011).