FZ volume:1 part:1 (1960) Annonaceae by N. K. B. Robson
A family of over 100 genera and over 1,000 species, almost confined to the tropical and subtropical regions of both hemispheres apart from Asimina in eastern N. America.
Trees, shrubs, or lianes (rarely rhizomatous shrublets), glabrous or with an indumentum of simple, stellate or lepidote hairs; bark usually smooth and entire, pale grey or buff to brown, the branches often reddish to purple-black with lozenge-shaped striations, pubescent or tomentose (rarely glabrous) when young; pith septate, oil cells present. Leaves alternate in two rows, entire, penninerved, membranous to coriaceous, exstipulate. Flowers morphologically terminal (i.e. terminal, supra-axillary, extra-axillary or leaf-opposed) or axillary, solitary or paired to fasciculate or cymose, on the young or old wood, sessile or pedicellate, more rarely pedunculate, actinomorphic, bisexual or more rarely unisexual, often fragrant. Sepals 3 (2), usually valvate in bud, free or ± united. Petals 6 (4) in two equal or ± unequal whorls (more rarely one whorl of 6, 4 or 3), imbricate or valvate (rarely open) in bud, free or ± united at the base, usually alternating with the sepals. Stamens ?, spiral, or 6–12 and whorled (sometimes staminodial) with anthers linear to semi-orbicular, lateral or extrorse (rarely apical); connective usually prolonged beyond the thecae, with the apex truncate, oblique, capitate, convex, conical or acute; filaments usually very short or absent, free, rarely more elongate and united in a cone over the gynoecium (Xylopia). Carpels ?–1 free or united at the base, or completely united to form a 1-locular ovary (Monodora); ovules ?–1: styles free or united, or absent. Fruit apocarpous with ripe carpels baccate (fleshy or lignified) or rarely dehiscent, stipitate or sessile, or syncarpous with either aggregated 1-seeded carpels or 1-locular and ?-seeded, Seeds vertical to horizontal, sometimes arillate, with abundant ruminate endosperm; embryo minute.
In addition to the above genera, Cananga odorata (Lam.) Hook. f. & Thorns, from tropical Asia is cultivated in our area.