Description from Flora of China
Hocquartia Dumortier; Isotrema Rafinesque.
Shrubs or herbs, rarely subshrubs or lianas, usually twining or climbing, rarely erect. Roots often tuberous. Stems woody or herbaceous. Leaves alternate, veins pinnate or palmately 3-7 from base, margin entire or 3-7-lobed. Flowers axillary, sometimes produced from old woody stems, solitary, fasciculate, or arranged in inflorescences. Perianth uniseriate, zygomorphic (in China). Calyx lobes fused; tube often enlarged at or near base to form a utricle, apically cylindric or funnel-shaped, rectilinear or curved; limb ligulate, discoid, or subpeltate; lobes 1-3 (less commonly to 6-dentate). Stamens 6 in 1 series, fully adnate to the style column to form gynostemium; filaments absent; anthers extrorse. Ovary inferior, 6-loculed, 6-angled; carpels fully connate; gynostemium 3- or 6-lobed. Fruit dry capsules, 6-valved, dehiscing from the apex (acropetally) or from the base (basipetally) [or rarely indehiscent]. Seeds flat or plano-convex, with or without wing, with fleshy funicle, persistent on seed as a membranous elaiosome.
Aristolochia jingiangensis H. Zhang & C. K. Hsieh (Acta Acad. Medic. Sichuan 15: 12. 1984) and A. faucimaculata H. Zhang & C. K. Hsien (loc. cit.: 13. 1984) are known to us by name only. Aristolochia blinii H. Léveillé, A. mairei H. Léveillé, A. viridiflora H. Léveillé, and A. viridiflora var. occlusa H. Léveillé are all Ceropegia mairei (H. Léveillé) H. Huber (Asclepiadaceae).
Wu Zhengyi (editor’s note) believes that species 1–29 should be transferred to the genus Isotrema.
Aristolochia macrocarpa C. Y. Wu & S. K. Wu ex D. D. Tao, Fl. Xizang. 1: 585. 1983 was missed in FOC vol. 5. Although it is a latter homonym, the name has been picked up and used in other regional floras, so future research will need to determine its placement.
About 400 species: widely distributed in tropical, subtropical, and temperate regions of the Old World, also in Australia; 45 species (33 endemic) in China.