3. Clematis terniflora de Candolle, Syst. Nat. 1: 137. 1817.
Sweet autumn clematis, yam-leaved clematis
Clematis dioscoreifolia H. Léveillé & Vaniot; C. dioscoreifolia var. robusta (Carr) Rehder; C. maximowicziana Franchet & Savatier
Stems climbing with tendril-like petioles and leaf rachises, 3-6 m. Leaf blade pinnately 3- or 5-foliolate; leaflets ovate or broadly lanceolate to narrowly deltate, to 6.5 × 3.5 cm, margins entire; surfaces abaxially glabrous or very sparingly appressed-strigose on major veins. Inflorescences axillary, 3-12-flowered cymes or compound cymes or paniculate with cymose subunits. Flowers bisexual, often some unisexual (staminate) in same inflorescence; pedicel 1-3.5 cm, slender; sepals wide-spreading, not recurved, white, linear or elliptic to lanceolate or narrowly obovate, 0.9-2.2 cm, length ca. 2-3 times width, abaxially tomentose along margins, adaxially glabrous; stamens ca. 50; filaments glabrous; staminodes absent; pistils 5-10. Achenes broad, flat, conspicuously rimmed, minutely appressed-silky, sometimes sparsely so; beak 2-6 cm.
Flowering summer (Jul-Sep). Roadsides, thickets, and other secondary sites, edges of woods near creeks; 0-1000 m; introduced; Ont.; Ala., Ark., Conn., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va.; native to Asia (China, Korea, Japan).
Clematis terniflora is commonly cultivated as an ornamental. It is widely naturalized in the eastern United States. The name C . paniculata J. F. Gmelin was incorrectly used for this species by Thunberg in 1794.
Some authors have recognized two or more varieties in this species, correlated with their distribution in Asia, but in the study by H.Hara (1975), all of the varietal names were reduced to synonymy.