Description from Flora of China
Herbs annual, erect. Leaves all basal, a few sessile, undivided and linear, others petiolate; leaf blade 3-sect, segments undivided or 1 or 2 × dissected into linear lobules. Scapes naked. Inflorescence a solitary terminal flower. Flowers bisexual, actinomorphic. Sepals 5, deciduous. Petals 3--5, yellow, narrowly obovate, clawed at base, with a nectary pit covered by a scale above claw. Stamens few to 10; filaments linear; anthers ellipsoid. Carpels 10 to numerous; ovule 1 per carpel; ovary attenuate into a subulate style. Aggregate fruit globose or cylindric; achenes 10 to numerous, spirally attached to elongated receptacle, with 2 hard hollow protuberances at base; style persistent, forming flattened spinelike beak.
Four species: N Africa, W Asia, Europe, SW Pacific Islands (New Zealand); two species in China.
(Authors: Wang Wencai; Michio Tamura)