Patches up to c.4 dm. diam.; plant glab. or nearly so. Lvs on very slender petioles ± 5-10 cm. long; lamina ± 10-20 × 15-25 mm., shallowly obscurely to distinctly 3-7-lobed; basal sinus narrow to rather open; lobes crenulate. Umbels (3)-5-10-fld on slender peduncles (5)-10-(25) mm. long (infl. rarely compound, of 2-3 umbellules). Fls subsessile, forming heads c. 5 mm. diam. Frs flattened, notched at base and apex, c.2 x 3mm., light brown; mericarps broadly winged on dorsal margin.

2n = 48

Perennial, forming large patches; stems slender or stout. Lvs simple, light glossy green, usually glabrous above and below, very rarely with 1-4 scattered hairs, (8)-10-30-(50) mm diam., divided to < ?-1/4 of radius into 7-9 segments; segments broadly ovate-oblong, shallowly crenate or ± entire; teeth with inconspicuous cartilaginous points; margins revolute; petiole glabrous or with a few retrorse hairs near blade. Umbels simple, 5-many-flowered; peduncle < or ± = lvs. Fls subsessile or shortly pedicellate. Fr. glabrous, 2.5-4 × 2-3 mm; dorsal rib broadly winged, acute; lateral ribs raised, slender.