Stem: base sparsely long-pubescent. Inflorescences usually with fewer than 16 flowers per branch. Flowers: sepals bright blue to light blue, lateral sepals 17-21 mm; lower petal blades 6-11 mm.

Flowering spring. Grassland, oak woods; of conservation concern; 0-500 m; Calif.

Delphinium variegatum subsp. thornei has an extremely restricted distribution, is very poorly known, and is imperiled by grazing. Delphinium parryi and D . variegatum subsp. kinkiense are the only other taxa of Delphinium naturally found on San Clemente Island.