Aristolochia rotunda, commonly known as smearwort or round-leaved birthwort, is a herbaceous perennial tuberous plant native to Southern Europe.
Etymology The genus name Aristolochia derives from the Greek words αριστος (aristos) meaning "the best" and 'lochéia' meaning 'childbirth', for the old use in promoting uterine contractions. The Latin name of the species rotunda refers to the rounded shape of the leaves.
Description
It grows to long, with slender, glabrescent, unbranched or branched stems. The root, a tuber, reaches in length and sometimes seems out of proportion to the slenderness of the plant. The stem has alternate, large, smooth-edged, heart-shaped, stalkless leaves long that clasp the stem with enlarged, basal lobes. The solitary flowers are tubular, about long, yellowish-green with a prominent, dark brown to dark purple flap, arising from the axils of the leaves; they have an unpleasant smell. The flowering period extends from April to June.
Reproduction The flowers of Aristolochia rotunda are hermaphrodite, and are pollinated by midges and other small insects (entomophily), attracted by the smell. The small hairs inside the cup prevent the flies from coming out and flying away. After the pollination these hairs sag and allow them to escape.
This species is a host plant of the caterpillars of an uncommon butterfly, the southern festoon Zerynthia polyxena. In eating the leaves of the plant, the larvae this insect ingest aristolochic acid that make them poisonous to birds.
Distribution This plant is common in Mediterranean countries from Spain east to European Turkey. It is naturalised very locally in southern England.
Subspecies Three subspecies are accepted: Aristolochia rotunda subsp. rotunda (autonym) Aristolochia rotunda subsp. insularis (E.Nardi & Arrigoni) Gamisans Aristolochia rotunda subsp. reichsteinii E.Nardi
Habitat This plant occurs along the banks of canals, edges of ditches and fields, sides of roads, meadows, slopes and forests. It prefers chalky soils and moist, shady areas, and grows at altitudes of above sea level.
Chemical constituents A. rotunda contains aristolochic acids which are carcinogenic, mutagenic, and nephrotoxic.
Gallery
References
Additional references Pignatti S. - Flora d'Italia - Edagricole – 1982, Vol. I, pag 135 Tutin, T.G. et al. - Flora Europaea, second edition - 1993 Björn Rulika, Stefan Wankeb, Matthias Nussa and Christoph Neinhuisb Pollination of Aristolochia pallida Willd. (Aristolochiaceae) in the Mediterranean - Flora - Morphology, Distribution, Functional Ecology of Plants - Volume 203, Pages 175-184
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