Proc. Amer. Acad. Arts 21: 364. 1886.
Stems glabrous. Leaves laminate and filiform-dissected; laminate leaf blades reniform in outline, deeply 3-parted, 0.5-0.8 × 0.9-1.5 cm, segments elliptic or obovate, margins sometimes notched; filiform-dissected leaves sometimes few and inconspicuous, stipules gradually tapering upward, connate for whole length, mostly petiolate. Flowers: receptacle glabrous; sepals spreading, 2-3 × 1-1.5 mm, glabrous; petals 5, 4-6 × 2-5 mm; style 1-1.5 mm. Fruiting pedicels recurved. Heads of achenes hemispheric, 3 × 4-5 mm; achenes 2-2.4 × 1.4-1.8 mm, glabrous; beak deciduous, sometimes leaving stub to 0.2 mm.
Phenology: Flowering late winter–spring (Mar–May).
Habitat: Shallow ponds and vernal pools
Elevation: 0-300 m
B.C., Calif., Oreg.