Trees or shrubs. Stipules 0. Leaves opposite, mostly simple and palmately-lobed, less often pinnate. Inflorescence racemose. Flowers actinomorphic, unisexual. Sepals 4-5. Petals 0 or equalling sepals. Stamens usually 8 in two whorls. Disk present. Ovary 2-locular and 2-lobed. Styles 2. Fruit a schizocarp, splitting into 2 samaras. Worldwide: 2 genera and 113 species in northern temperate regions and on tropical mountains. Britain: 1 genus and 16 taxa. |