ARISTOLOCHIACEAE (Birthwort Family)
herbs or lianas (shrubs elsewhere). Leaves alternate, simple, with petioles.
Flowers perfect, epigynous. Calyx usually petal-like (not green), often united
into a straight or contorted tube toward the base, expanded into 3 shallow or
deep lobes at the tip. Corolla absent (reduced to small scales elsewhere).
Stamens (5)6 or 12. Pistils 1 per flower. Ovary inferior, 3–6-locular,
the ovules numerous. Style 1, the stigmas 3–6. Fruits capsules with
numerous seeds. Five genera, about 600 species, nearly worldwide but most
diverse in tropical and subtropical regions.