Aristolochiaceae

Abstract

Woody or herbaceous perennials, often twining when woody, rhizomatous when herbs. Leaves alternate (spuriously opposite in Asarum), distichous, conduplicate in bud, exstipulate (sometimes “pseudostipules” present), usually petiolate, the blade simple, mostly undivided and entire, often cordate or reniform, occasionally 3-lobed, 2-lobed or palmately to pedately lobed. Flowers solitary or in rhipidia, terminal or axillary, not rarely from the old wood; perfect, mostly epigynous, rarely half epigynous or almost hypogynous; perianth usually uniseriate, biseriate in Saruma, mostly gamophyllous, trimerous or monomerous, very rarely 6-merous, actinomorphic or zygomorphic; stamens 5 to more than 40, arranged in 1–4 whorls, commonly 6 or 12 in one or two series respectively, distinct, or the filaments connate or stamens entirely fused with the style forming a gynostemium; anthers tetrasporangiate, often produced into an appendage exceeding the thecae, extrorse or those of the outer whorl nearly latrorse; ovary syncarpous (apocarpous in Saruma), 4- to 6-locular; style 3-to 6-lobed, or divided in numerous branches (Saruma with styluli); ovules numerous in each locule (few in Euglypha), centrally attached, horizontal or pendulous, anatropous, apotropous, and bitegmic. Fruit usually capsular, septicidal, or irregularly dehiscent, follicular in Saruma, an indehiscent, thick-walled and rather dry berry in Pararistolochia, a schizocarp in Euglypha. Seeds with abundant, oily, starch-free endosperm and a minute but well-developed embryo; seed coat with the mechanical tissue derived from both integuments.