XVII. ANONACEÆ.
Trees or shrubs, with watery juice, slender terete branchlets marked by conspicuous leaf-scars, and fleshy roots. Leaves alternate, conduplicate in the bud, entire, feather-veined, petiolate, without stipules. Flowers perfect, solitary, axillary or opposite the leaves; sepals 3, valvate in the bud; petals 6, in 2 series, imbricated or valvate in the bud; stamens numerous, inserted on the subglobose or hemispheric receptacle, with distinct filaments shorter than their fleshy connectives terminating in a broad truncate glandular appendage; anthers introrse, 2-celled, opening longitudinally; pistils inserted on the summit of the receptacle; ovary 1-celled; ovules 1 or many, anatropous. Fruit baccate or compound. Seeds inclosed in an aril; seed-coat thin, crustaceous, smooth, brown, and lustrous; albumen ruminate, deeply penetrated by the folds of the inner layer of the seed-coat; embryo minute; radicle next the hilum. Two of the forty-eight or fifty genera of the Custard-apple family, confined almost exclusively to the tropics and more numerous in the Old World than in the New, occur in North America.
CONSPECTUS OF THE NORTH AMERICAN GENERA.
Petals imbricated in the bud; ovules numerous; fruit developed from one pistil.1. [Asimina.] Petals valvate in the bud; ovule solitary; fruit developed from several confluent pistils.2. [Anona.]