Leafl. W. Bot. 10: 133. 1964.
Annuals 4–15 cm. Stems erect. Leaf-blades oblong, margins crenate. Inflorescences ± finely scaly, usually sparsely, finely glandular; nodes 1–3-flowered; flowers not crowded; distalmost bracts linear, 2–3 mm. Pedicels ascending to spreading, proximalmost longer than calyx, distalmost equal to calyx, visible. Flowers: caly× lobes lanceolate, slightly surpassing capsule, ape× blunt to rounded, inner face white-hairy; corolla purple, lobes purple, rarely white, throat white with red-purple spots at base of banner, 4.5–8 mm, glabrous; banner length 1 times wings, lobe base without folds; stamens: abaxial filaments glabrous, adaxials sparsely hairy, basal spur 0. Seeds 6–8, oblong, 1.5–2 mm, margins thickened, inrolled. 2n = 14.
Phenology: Flowering Mar–Apr.
Habitat: Margins of oak scrub on screes.
Elevation: 200–400 m.
Collinsia antonina is geographically narrowly endemic, known only from Monterey County. It occurs on scree derived from whitish siliceous shale of the Monterey Formation at the edge of woodlands near the shade of Quercus john-tuckeri. It is morphologically similar to C. parryi, which lacks the coarse white hairs on the inner face of the sepals. DNA studies (B. G. Baldwin et al. 2011) show a more distant relationship between C. antonina and C. parryi than suspected from morphology alone.