Tufted ± pilose herb up to 3 dm. tall, sparingly to much branched. Stock very stout; main roots stout, fleshy, full of milky juice; main stems stout, ± pilose, up to c. 1 dm. long or more. Radical lvs on petioles 5-15 cm. long with stout broad sheaths; lamina ± reniform in outline, 5-15 cm. diam., ternatisect; divisions stalked, ± divided into cuneate segs ± 1 cm. × 5-10 mm., abruptly acute. Cauline lvs similar, subsessile. Infl. of a solitary fl. or 2-4 together. Fls 3-7 cm. diam. Sepals narrow-oblong, villous, us. 5, becoming reflexed, 15 × 3 mm. Petals 15-20 or more, narrow-oblong to narrow-obovate, white, 2 cm. × 5 mm. rounded at apex. Nectary gland small, basal. Fruiting head subglobose, 1-2 cm. diam. Achenes brown, pilose to glabrate, turgid, obliquely obovoid, ± 2 × 1 mm. Style slender, ± 5 mm. long.

2n = 48

Tufted perennial; rhizome stout. Stem erect, with silky hairs or almost glabrous, 20-30 cm tall. Lvs 1-2-ternate, fleshy, glaucous, 10-20 cm diam., with silky hairs; lobes toothed or divided. Fls 1-3 per stem, 4-6 cm diam.; pedicels hairy. Sepals spreading, hairy. Petals 15-25, white, linear-oblong; nectary single, 1-2-(4) mm from petal base, naked. Receptacle hairy. Achenes very numerous, not flattened, hairy; body 2-3 mm long; beak straight or curved, 4-6 mm long.