English: Smearwort; Round-leaved birthwort.
Region: Southern Europe, Mediterranean, rarely naturalized in the British Isles.
Habitat: along the banks of canals, edges of ditches and fields, sides of roads, meadows, slopes and forests; prefers chalky soils, moist, shady areas; altitude of 0 to 800 metres.
Content: aristolochic acids, carcinogenic, mutagenic, nephrotoxic.
Ecology: only host plant of Zerynthia polyxena.
Use: medicinal.
BotanyHerb; climbing.
Root: 5 to 25 cm long; seems out of proportion to the slenderness of the plant.
Stem: unbranched.
Leaves: alternate, large, smooth-edged, heart-shaped, stalkless; clasp the stem with enlarged, basal lobes.
Flowers: hermaphrodite; solitary; unpleasant odor; tubular; 2.5 to 5 cm long; yellowish-green; prominent, dark-brown or dark purple flap; arising from the axils of the leaves; flowering from April through June.
Pollination: by midges, small insects, attracted by the smell and by purple-brown color of the flowers.