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Aceraceae


This small family is widespread and sometimes dominant in cold and temperate regions of the Northern Hemisphere. It is represented in Australia by a few species of introduced maple, occasionally naturalised in temperate parts of Victoria, Tasmania and other southern States.

Characteristic features of the family Aceraceae in Australia include:

  • winter-deciduous trees
  • leaves opposite, usually palmately-divided
  • flowers small, 5-partite, greenish or yellowish, with a prominent disc
  • ovary superior, developing into winged fruits (samaras) in pairs

Description

Deciduous or semi-deciduous trees, glabrous or with simple, non-glandular, unicellular hairs. Leaves opposite, petiolate. Stipules absent. Lamina simple or trifoliolate, symmetric, palmatifid or palmatisect, ovate to orbicular; base cordate; margins crenate, dentate or serrate; venation palmate, with the midrib conspicuous, and the tertiary venation reticulate; surfaces not punctate; herbaceous. Plants monoecious, dioecious or with bisexual flowers and male flowers occurring together on the same plant. Inflorescences terminal, consisting of racemes or panicles. Bracts and bracteoles absent. Pollination by insects. Flowers stalked. Floral disc present or absent; nectaries present on the disc. Perianth regular, of 2 dissimilar whorls or the petals lacking, imbricate in bud. Calyx segments free, with 5 sepals, herbaceous or membranous. Corolla when present free, with 5 petals, alternating with the sepals, white, cream, yellow or green, membranous; claws present or absent; lobes ±entire. Fertile stamens (6) 8, both alternating with and opposite to, or not clearly correlated with, the sepals, free of the corolla, free of the ovary and style, distinct from each other, all ±equal. Anthers dorsifixed, versatile or not versatile, opening inwards by longitudinal slits; 2-celled. Ovary superior and sessile. Carpels 2, fused; ovary with 2 locules. Style terminal, single, unbranched or branched above or from the base. Ovules 1 or 2 per locule, sessile; placentation axile. Fruit a dry 2-winged schizocarp (samarium), disseminating by 1-winged mericarps or rarely as a whole fruit; the perianth on the maturing fruit deciduous. Disseminule winged; micro-surface ±smooth, yellow, green or brown, dull. Seeds 2 per fruit. Aril absent. Cotyledons 2. Embryo straight.
(Note: this description has been generated from the coded data compiled for the key. Any errors in the key data will be reflected in the descriptions.)

A treatment of the family Aceraceae has been published in:
Flora of Australia 25: 164-165.

Australian genera of Aceraceae (as recognised for the Flora of Australia)

* = all species introduced

*Acer


Acer sp. (autumn branch)
Photo: anon NSW National Herbarium