Physocarpum Berchtold & J. Presl; Praticola Ehrhart; Ruprechtia Opiz (1852), not C. A. Meyer (1840); Schlagintweitiella Ulbrich; Tripterium Berchtold & J. Presl.

Herbs perennial, from woody rhizomes, caudices, or tuberous roots. Leaves basal and cauline, proximal leaves petiolate, distal leaves sessile; cauline leaves alternate. Leaf blade 1--4-ternately or -pinnately compound, rarely simple (Thalictrum rotundifolium); leaflets cordate-reniform, obovate, lanceolate, or linear, sometimes lobed, margin entire or crenate. Inflorescences terminal, sometimes also axillary, monochasial cymes, or sometimes racemelike, paniculate, flat topped, or umbel-like, 1--200-flowered; involucres absent or present, involucral bracts 2 or 3, leaflike, often resembling a whorl of 6--9 simple bracts, not closely subtending flowers. Flowers usually all bisexual, rarely bisexual and unisexual (T. smithii), or all unisexual (not in China), radially symmetric; sepals 4--10, whitish to greenish yellow or purplish, lanceolate to reniform or spatulate, flat, 1--18 mm, not persistent in fruit; petals absent; stamens 7--70; filaments filiform to clavate or distally swollen; staminodes absent; carpels 1--50(--70), 1-ovulate; style usually present and persistent, less often absent. Fruits achenes, usually aggregated, sessile or stipitate, fusiform to ovoid, obovoid, falcate, or discoid, laterally prominently ribbed; persistent style (when present) forming straight to circinately coiled beak. x = 7.

Our understanding of the genus Thalictrum is far from complete. Numerous species and varieties are poorly defined owing to insufficient field studies and because highly variable characters have been used as diagnostic features in the literature. Useful characters in identifying species of Thalictrum include leaflet shape, indumentum (glands and/or hairs) of leaves and achenes, degree of dilation of filaments, anther length, shape of anther apex, and achene shape and venation patterns. Leaflets described in this treatment are the terminal, ultimate ones on the main rachis of leaves at the middle of the stem (where available); proximal and distal leaves on the stem are more variable and are often not representative of the species. Filament and stigma colors cited refer to fresh material.

Thalictrum punduanum Wallich (Pl. Asiat. Rar. 2: 26. 1831), from NE India and N Thailand, has not yet been recorded from China, but might be expected to occur in Xizang and/or Yunnan.

Thalictrum ussuriense Luferov (Bjull. Moskovsk. Obshch. Isp. Prir., Otd. Biol., 94(5): 103. 1989) was described from the Far East region of Russia and was also said to occur in NE China and N Korea. However, no Chinese specimens have been seen by the current authors, and the species is therefore not described here.

The identities of the taxa to which the following names apply could not be ascertained. All were described from China, but none of the types has been seen by the present authors: Thalictrum micrandrum Hayata (Icon. Pl. Formos. 3: 4. 1913), described from Taiwan; T. morii Hayata (Icon. Pl. Formos. 3: 5. 1913), described from Taiwan; T. oshimae Masamune (J. Soc. Trop. Agric., Taiwan 6: 569. 1934), described from Taiwan; T. pumilum Ulbrich (Bot. Jahrb. Syst. 48: 623. 1913), described from Yunnan; T. rockii B. Boivin (J. Arnold Arbor. 26: 115. 1945), described from Gansu and Qinghai; and T. silvestrii Pampanini (Nuovo Giorn. Bot. Ital., n.s., 22: 291. 1915), described from Hubei.

Thalictrum sinense Loureiro (Fl. Cochinch. 1: 346. 1790) was regarded by Merrill (Trans. Amer. Philos. Soc., n.s., 24(2): 403. 1935) as a doubtful species and certainly not a Thalictrum.

About 150 species: worldwide, mainly in temperate regions; 76 species (49 endemic) in China.

(Authors: Fu Dezhi)