Lianas or climbing shrubs; white or clear latex in all parts (except in A. zambesiaca and occasionally A. schumannii); branches mostly lenticellate; branchlets terete, glabrous or sometimes puberulous. Leaves opposite, petiolate; ochreae often widened into intrapetiolar stipules. Inflorescence terminal, sometimes also axillary, cymose, few- or many-flowered, lax to very dense; peduncle mostly short; flowers open during the day, mostly fragrant. Sepals connate at the extreme base, ciliate, mostly with colleters within. Corolla with variously shaped heads in mature bud more or less characteristic for the species, mostly pubescent below the insertion of the stamens and interrupted between the filament ridges; lobes overlapping to the right in bud, ciliate; tube shorter or longer than the lobes; lobes entire to sinuate-crenate, spreading or recurved; stamens with their tips reaching mouth of corolla tube; anthers sessile, sterile at the apex and below, pubescent below, coherent with the pistil head by a clavuncle; ovary of two separate carpels (united in A. multiflora), pubescent at the apex; disk absent; pistil of a basal cone or cylinder, usually with a ring at the apex and a bilobed stigmoid apex. Fruit of two separate, thin walled, long and linear follicles (1 syncarpous in A. multiflora), dehiscent on adaxial side; seeds with a short wing at the base and a hairy coma longer than the grain attached at the apex or on a beak at the apex.