Herbs or
vines perennial; rhizomatous or not.
Leaves cauline or basal; blades simple, unlobed, margins entire; petiolate; stipules 0.
Inflorescences solitary flowers.
Flowers bisexual; calyces enlarged, fused, petaloid, 3-lobed, tubes inflated, straight or curved; corollas reduced to scales or lacking; stamens 6 or 12, free or adnate to styles and stigmas, thereby forming gynostemia, anthers extrorse; pistils 6-carpellate, ovaries inferior.
Fruits capsules, regularly to irregularly dehiscent.
Seeds often flattened; endosperm copious.
Mainly tropical and temperate regions worldwide. 5 genera; 1 genus treated in Flora.
as described under Aristolochiaceae
Herbs or lianas [shrubs, rarely trees], deciduous or evergreen, often aromatic. Wood with broad medullary rays. Leaves alternate, simple, petiolate. Leaf blade unlobed, margins entire. Inflorescences terminal or axillary, racemes or solitary flowers, rarely fan-shaped cymes. Flowers bisexual; calyx enlarged, petaloid, usually tubular, [1-,] 3-, [6-, rarely 5-]merous, lobes valvate; corolla usually reduced to scales or absent; stamens 5, 6, or 12 [multiples of 3 or 5], free or adnate to styles and stigmas, forming gynostemium; anthers extrorse; pistil 1, 4-6-carpellate; ovary inferior, partly inferior, or superior; placentation axile (and ovaries 4-6-locular) or parietal; ovules many per locule, anatropous. Fruits capsules [follicles], regularly to irregularly loculicidal, rarely indehiscent [septicidal]. Seeds often flattened; endosperm copious.