Herbs, perennial, cespitose, green to ashy olive when dry, to 3.8 dm, not glaucous. Stems branched, with 1-2 nodes, 1.5-5.3 mm wide, glabrous, margins entire to denticulate apically, similar in color and texture to stem body; first internode 11-33 cm, usually equaling or longer than leaves; distalmost node with 2-3 branches. Leaf blades glabrous, bases not persistent in fibrous tufts. Inflorescences borne singly; spathes green, obviously wider than supporting branch, glabrous, keels entire to denticulate; outer 14-30 mm, usually 2-7 mm longer than inner, tapering evenly towards apex, margins basally connate 4-7.6 mm; inner with keel evenly curved to straight, hyaline margins 0.1-0.7 mm wide, apex abruptly widening, ending 0.2-1.3 mm proximal to green apex. Flowers: tepals light blue to dark bluish violet or rarely purplish or white, bases yellow; outer tepals often broadly cuneate, 10-17 mm, apex rounded, truncate, or occasionally emarginate, aristate; filaments connate ± entirely, usually glabrous; ovary similar in color to foliage. Capsules tan to dark brown, globose to obovoid, 3-5 mm; pedicel erect to ascending. Seeds globose to obconic, lacking obvious depression, 1.5-2.2 mm, rugulose. 2n = 32.

Flowering early spring--late summer. Open, mostly moist, grassy areas and woods; 0--2400 m; Calif., Oreg.; Mexico (Baja California).

Sisyrinchium bellum is the most common species of Sisyrinchium in California; it is highly variable in habit, flower color, and size. Plants of serpentine areas are intermediate with S. idahoense var. idahoense; plants of the Transverse Ranges are intermediate with S. demissum.