Order XXXIV. Aristolochiaceae, Lindley.—Birthworts.
Aristolochieae, Jussieu; Asarinae, Bartling.
Characters.—Flowers hermaphrodite, axillary, solitary. Calyx adherent (superior), tubular, monosepalous, with the segments valvate or induplicate in aestivation, sometimes regular, sometimes very unequal. Stamens 6 to 12, epigynous, distinct, or adhering to the style and stigmas. Ovary inferior, 6-celled, very rarely 3—4-celled; ovules numerous, anatropal, horizontally attached to the axis. Style simple. Stigmas radiating, as numerous as the cells of the ovary. Fruit dry or succulent, 3—4—6-celled, many-seeded. Seeds thin, with a very minute embryo placed at the base of fleshy albumen—Herbs or shrubs, the latter often climbing. Wood without concentric zones and inseparable wedges. Leaves alternate, simple, stalked.
Properties.—Not important. The roots possess stimulant properties, owing to the presence of volatile oil. Some of them are acrids. Bitter extractive renders them somewhat tonic.