Stems proximally puberulent with arched hairs. Inflorescences generally more than 25-flowered, dense; pedicel ascending. Flowers: sepals dark blue-purple, spreading to erect, lateral sepals 7-10 mm, less than 4(-5) mm wide, spurs 8-12 mm; lower petal blades 3-5 mm. Fruits 2.2-2.5 times longer than wide. 2 n = 16. Flowering early summer. Grassland, open pine woods; of conservation concern; 1100-1500 m; Calif. Delphinium hesperium subsp. cuyamacae is local near Cuyamaca Lake. Although it has been reported also from Mt. Palomar, specimens have not been seen. No other Delphinium with similar features grows in the region where D . hesperium subsp. cuyamacae grows. Superficially, specimens of this taxon resemble those of some D . hansenii subsp. hansenii . Seeds are quite different, as are pubescence patterns and venation on abaxial surface of leaves. Delphinium parryi occurs near D . hesperium subsp. cuyamacae ; flowers of D . parryi in that area are much larger and more widely spaced on the inflorescence than in D . hesperium subsp. cuyamacae .