Caudices branching, 1.5-2 cm diam. Leaves: rosettes 5-40; blade linear, subterete, 4-8 × 0.2-0.8 cm. Inflorescences: floral shoots 5-15(-20) × 0.1-0.4 cm; proximalmost leaf blades 4-20 mm; branches 2-4, 1-3 times bifurcate. Pedicels 3-9(-17) mm. Flowers: calyx 4-6 × 4-6 mm; petals connate 1-3 mm, bright yellow, not lineolate, 5-13(-17) × 2-4 mm, tips spreading. 2n = 34.

Flowering late spring. Xeric limestone outcrops; of conservation concern; 1500-1700 m; Calif.

Subspecies costatifolia is known from one southwest-facing outcrop of pre-Cretaceous limestone just west of Pierpoint Springs, Tulare County, in the southern Sierra Nevada, in an area that has been subdivided; it is considered to be fairly threatened (California Native Plant Society, http://cnps.web.aplus.net/cgi-bin/inv/inventory.cgi).

Subspecies costatifolia forms clumps to 10 cm in diameter. The bright yellow corolla and more-branching cyme and sometimes longer pedicels set it apart from the other subspecies of Dudleya abramsii and approach D. cymosa, where the original authors placed it. The cespitose small rosettes of narrow leaves have much more the aspect of D. abramsii, especially recalling the lowland subsp. bettinae, and the higher insertion of the antisepalous stamens is a mark of D. abramsii (and the related D. parva in contrast to D. cymosa and other species). The branching cyme is somewhat approached in subsp. calcicola, which grows just to the north.