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.

參考文獻

作者

CHEN, CHING-HSIA

型態特徵

Trees, shrubs, vines or rarely herbs. Leaves usually alternate, pinnately or palmately compound, rare simple; stipules none or in some climbing species present. Flower usually small, unisexual or bisexual, in racemes, panicles or corymbs, actinomorphic or commonly zygomorphic; calyx 4–5, imbricate or valvate sepals; petals 4–5 or wanting, often with hairs or scales at the base inside; hypogynous discs well developed, situated between petals and stamens; stamens usually 8–10, the filaments distinct or united at base; ovary superior, 2–4-celled, with one or more ovules in each cell; placentation axile or parietal, the style simple or divided. Fruit various, drupaceous or capsular, entire or lobed, sometimes winged. Seeds often arillate globose or compressed, albuminous or exalbuminous.

參考文獻