特徵描述
作者
LI, HUI-LIN and LO, HANN-CHUNG
型態特徵
Trees or shrubs, unarmed, without latex; branches pertaining green. Leaves opposite, estipulate, simple or pinnately compound. Flowers in axillary or terminal racemes, panicles, corymbs, umbels or spikes, andropolygamous and monoecious or dioecious, or unisexual and dioecious, seemingly bisexual, actinomorphic, usually 4–5 merous; sepals free, overlapping in bud; petals sometimes none, mostly equal in number to the sepals, overlapping in bud, at the base without a scale; disk annular, lobed; stamens 4–12, usually 8, on, around or within the disk; filaments free, filiform; anthers inserted in a basal cleft or medifixed; cells 2, longitudinally dehiscent; ovary superior, 2-lobed, 2-celled, compressed contrary to the septum; ovules 2 in each cell, orthotropous to anatropous; styles 2, or one 2-armed. Fruit a samara; mericarps 2, separating when ripe, winged on the endosperm; embryo with folded cotyledons.
屬
A family of 3 genera, about 200 species, mainly in north temperate zone.
