Aristolochia

Aristolochia 

a genus of plants of the family Aristolochiaceae (birthwort). The plants are perennial herbs, often with climbing stems, and woody lianas. The leaves are alternate and cordate. The flowers are in the axil. The perianth, which is irregular, corolliform, tubular, and inflated at the base, generally has an entire ligulate fold at the top. There are six stamens, adnate to the style. The flowers are adapted for cross-pollination by insects. There are approximately 350 species (according to other data, up to 500), distributed in the tropical and, more rarely, temperate regions. In the USSR there are seven species, the best-known being Aristolochia clematitis, which grows in the forests, thickets, and meadows of the Caucasus and the central and southern European USSR; this species is poisonous. Dutchman’s-pipe (A. macrophylla, formerly A. sipho) is cultivated as an ornamental climbing plant.