Annuals, to 40 cm. Stems erect, branched distally, glabrous or sparsely hairy. Leaves linear, 10-80 × 1-2+ mm (simple blades or single lobes), margins entire or pinnately lobed, faces glabrous. Involucres hemispheric or obconic, 6-10 mm. Phyllaries 12-18 (connate ¹/4-¹/2 their lengths), ± lanceolate, puberulent to glabrate. Receptacles dome-shaped or obconic, densely hairy. Ray florets 6-13; laminae oblong to oval, 5-10 mm. Anther appendages linear to ± ovate. Cypselae black or gray (reflective), clavate, to 1.5 mm, glabrous; pappi 0. 2n = 12.

Flowering Mar-Jun. Vernal pools and wet meadows; of conservation concern; 0-100 m; Calif.

Lasthenia conjugens often germinates under water in vernal pools; first leaves are submerged and entire; later, aerial leaves are pinnatifid.