特徵描述
作者
LIAO, JIH-CHING
型態特徵
Monoecious deciduous trees and shrubs. Leaves alternate, simple, straight-veined, petioled; stipules fugacious. Staminate flowers in long pendulous catkins, 1–6 clustered together in axils of bracts; calyx 2–4, parted or not; stamens 2–20; pistillate flowers in short lateral or capitate catkins, with or without calyx, adnate to the ovary; ovary 2-celled, each cell with 1 ovule; style 2-parted. Fruit a nut or samara, indehiscent, 1-celled, 1-seeded.
屬
Six genera and about 150 species mostly in the northern hemisphere, some planted for ornament and others for the edible nuts.
參考文獻
Alnus 赤楊屬
作者
LIAO, JIH-CHING
型態特徵
Monoecious deciduous trees or shrubs; bark scaly; winter buds stalked, with 2–3 scales. Leaves serrate or dentate, penninerved. Staminate catkins appearing in the preceding season, solitary or panicled, pendulous or erect, naked during winter; staminate flowers 3–6, clustered in axil of bract; calyx 4-parted; stamens usually 4, rarely 1–3; anthers subsessile, undivided; pistillate spikes short, erect; pistillate flowers clustered; ovary 2-celled, each with 1 ovule; styles 2, tip stigmatose. Fruit (strobiles) woody, ovoid or ellipsoid, cone-like, with persistent truncate to 3–5-lobed bracteloes; nutlets compressed, with or without narrow wings, 1-seeded.
