Acer L.

TSO logo

Sponsor this page

For information about how you could sponsor this page, see How You Can Help


Article from Bean's Trees and Shrubs Hardy in the British Isles

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Acer' from the website Trees and Shrubs Online ( Accessed 2020-06-01.


  • Sapindaceae (formerly Aceraceae)

Common Names

  • Maples


The author(s) of a plant name. The names of these authors are stated directly after the plant name often abbreviated. For example Quercus L. (L. = Carl Linnaeus); Rhus wallichii Hook. f. (Hook. f. = Joseph Hooker filius i.e. son of William Hooker). Standard reference for the abbreviations: Brummitt & Powell (1992).
Made up or consisting of two or more similar parts (e.g. a compound leaf is a leaf with several leaflets).
(botanical) Contained within another part or organ.
(of fruit) Vernacular English term for winged samaras (as in e.g. Acer Fraxinus Ulmus)
Small nut. Term may also be applied to an achene or part of a schizocarp.
Roughly hand-shaped; (of a leaf) divided partially or fully to the base with all the leaflets arising from the tip of the petiole (as in e.g. Aesculus).
(sect.) Subdivision of a genus.
(of a leaf) Unlobed or undivided.
Classification usually in a biological sense.
Having only male or female organs in a flower.


There are currently no active references in this article.


Article from Bean's Trees and Shrubs Hardy in the British Isles

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Acer' from the website Trees and Shrubs Online ( Accessed 2020-06-01.

Acer is one of the most significant tree genera of the northern hemisphere. The 156 species occur in North America south to Mexico, in Europe and North Africa, and from the Middle East through the Himalaya to southeastern Asia (de Jong 2002). Though it is primarily a temperate genus, species of Acer occur in tropical Asia, crossing the equator on Java. They are trees or shrubs, grown primarily for their leaves, which display an array of shapes, sizes and colours. Bark is extremely variable and often diagnostic; it may be smooth, ridged or flaky, seldom rough or forming plates, an exception being the coarse exfoliating plates of A. yui. Bud scales are often large and foliose with 2–15 pairs, eventually caducous. The leaves are deciduous or evergreen, opposite and typically palmate with five lobes, although they may be entire or with 3–13 lobes, or they may be pinnate with three, five or rarely seven leaflets. Hairs are usually present in the vein axils of the leaf undersides and often elsewhere. Stipules are absent (present in A. saccharum subsp. nigrum). Inflorescences are extremely variable in form – compound or simple, corymbose, paniculate, racemose or umbellate – and are produced in terminal and/or lateral positions. Flowering occurs before or as the leaves emerge. The flowers are hermaphrodite or unisexual (trees sometimes dioecious). They have (four to) five (to six) sepals, (four to) five (to six) petals (rarely none), the sepals and petals sometimes fused together, usually yellowish or green, though some species have contrasting white petals and green or red sepals; (4–)8(–13) stamens, nectaries forming a fleshy disc or ring in the centre of the flower; the stamens may be inserted inside or outside the ring or, more commonly, emerge from the ring itself. The fruit is a two-seeded schizocarp, a dry indehiscent structure that breaks up at maturity into single-seeded sections. These sections each have a single wing and are known as samaras (van Gelderen et al. 1994, de Jong 2002). Development of the samara proceeds directly after flowering, and large but immature fruits are often a conspicuous feature of the trees through the summer. In the following account the entries for fruiting time refer to ripening.

Despite the interest of horticulturists, Acer has not been a subject for recent academic botanical study, and a modern revision is urgently needed to clarify the systematic position of many taxa. The taxonomy in this account is generally based on Piet de Jong’s classification in the current standard reference Maples of the World (van Gelderen et al. 1994), although this differs in some respects from other major authorities such as the recently available Flora of China account (Xu et al. 2008); some modifications have been included in the present work on the advice of Peter Gregory, in advance of his own forthcoming book on maples (Gregory, in prep.). A summary table of the infrageneric classification of Acer is provided below, which helps place unfamiliar species with better-known relatives, but for more detail Maples of the World should be consulted. A number of familiar species with multiple subspecific taxa are included, as some of the names are unfamiliar and represent recent collections. For these species simple keys covering the important characters are provided. Almost all species mentioned in this account are illustrated (mostly by colour photographs) in Maples of the World, its companion volume Maples for Gardens (van Gelderen & van Gelderen 1999), and An Illustrated Guide to Maples (le Hardÿ de Beaulieu 2003).

Bean's Trees and Shrubs



A large and important genus composed chiefly of deciduous trees, some being of the largest size, many middle-sized or small, a few shrubby. The hardy species are widely spread over the three northern continents, the finest trees being natives of N. America. A large number come from E. Asia, many of which, however, are small trees.

The most constant and distinctive characters of the genus are the opposite leaves and the form of the fruits. Each fruit consists normally of two sections, known as samarae (commonly as 'keys'), attached to each other by their bases, and each 'key' consists of a nutlet, containing one, sometimes two, seeds, and a large, thin, membranous wing. These wings assist in the dispersal of the seed. The flowers are sometimes unisexual. The typical maple leaf is broad and flat, with five palmate lobes. But there is a great diversity of shape in the genus: some species have as many as eleven or thirteen lobes to each leaf, many have but three lobes, and there is a distinct group with leaves not lobed at all. Finally comes the section of maples with compound leaves consisting of three or five distinct leaflets, sometimes kept genetically separate as Negundo.

Most of the maples have tamely coloured flowers, varying from yellow to greenish white; a few have purple flowers (like A. circinatum), and are very ornamental when in blossom; whilst others, like A. opalus, flower in early spring before the leaves expand, and although not highly coloured make, at that season especially, a pleasing display. Still, on the whole, the attractions of the maples generally are in the large or handsomely cut foliage, and in the red or yellow tints many of them assume in autumn.

Few trees are more easily cultivated than these, their chief requirements being a rich moist soil and a moderately sunny, or at any rate not unduly shaded, position. Some of the smaller species, however, like A. rufinerve, A. capillipes, and A. argutum, like their stems shaded. All the maples should, if possible, be raised from seeds; if grafting has to be resorted to, as for the numerous coloured-leaved and variously habited varieties, the scions should be worked on stocks of their own species.

The number of species of maple has so largely increased in this century by introductions from China that even the largest garden could not accommodate them all, though no other genus of hardy broad-leaved trees is so varied or has so many species that are worthy of cultivation. The following is a short selection:

Large and Medium-sized Trees: A. cappadocicum 'Aureum', 'Rubrum' and var. sinicum; A. heldreichii; A. lobelii; A. monspessulanum; A. opalus; A. platanoides, A. p. 'Goldsworth Purple', 'Crimson King' or 'Faasen's Black', A. p. 'Drummondii'; A. pseudoplatanus 'Atropurpureum' (syn. 'Purpureum Spaethii'); A. rubrum; A. saccharum; A. saccharinum (but the brittle wood makes it unsuitable for town-planting); A. trautvetteri; A. × zoeschense.

Small Trees and Shrubs: A. argutum; A. circinatum; A. cissifolium; A. davidii; A. forrestii; A. griseum; A. grosseri var. hersii; A. japonicum, A. j. 'Aureum' and 'Vitifolium'; A. negundo and its cultivars; A. nikoense; A. palmatum and its cultivars; A. pensylvanicum; A. pseudoplatanus 'Brilliantissimum'; A. rufinerve; A. triflorum.

From the Supplement (Vol.V)

It was remarked on page 185 that 'no other genus of hardy broad-leaved trees is so varied or has so many species that are worthy of cultivation.' Fifty-four pages were devoted to describing those in cultivation, but many more would have been needed to do full justice to the genus had the treatment been prepared at the present time. This is largely thanks to the new introductions by Gordon Harris, who has built up a remarkably comprehensive collection of maples at Mallet Court in Somerset, which includes numerous cultivars of A. palmatum previously unknown in this country. Most of these are mentioned in this supplement.

It is indisputable that many species recognised in the present edition are closely related to others named earlier and merit only subspecific rank. The relevant synonyms are added in this supplement, but it must be emphasised that not all the new combinations made by Dr Murray would necessarily be accepted by other botanists working on the genus, though the majority probably would be.

Recent Literature

(I.D.S.Y.B. International Dendrology Society Year Book)

Banks, R. A. – 'Some Maples at Hergest Croft, Herefordshire', I.D.S.Y.B. 1971 pp. 8-13.

de Jong, P. C. – 'Flowering and Sex Expression in Acer L.' Medel. Landbouwhogeschool, Wageningen, No. 76-2 (1976). An important contribution to our knowledge of the genus, with a proposed classification.

Harris, J. G. S. – 'Maples in my Garden', I.D.S.Y.B. 1971, pp. 14-23.

Harris, J. G. S. – 'Maples in Taiwan and Hong Kong', I.D.S.Y.B. 1972, pp. 59-62.

Harris, J. G. S. – 'Propagation of Acers', I.D.S.Y.B. 1973, pp. 57-61.

Harris, J. G. S. – 'Maples from Japan', Journ. R.H.S., Vol. 199, pp. 394-9 (1974).

Harris, J. G. S. – 'Growing Maples from Seed', The Garden (Journ. R.H.S.), Vol. 101, pp. 503-6 (1976).

Harris, J. G. S. – 'Japanese Maples', The Plantsman, Vol. 3, pp. 234-50 (1982).

Harris, J. G. S. – 'An Account of Maples in Cultivation', The Plantsman, Vol. 5, pp. 35-58 (1983).

Lamb, J. E. D., and Nutting, F.J. – 'Propagation Techniques in the Genus Acer', The Plantsman, Vol. 5 (3), pp. 186-92 (1983).

Lancaster, Roy – 'Maples of the Himalaya', The Garden (Journ. R.H.S.), Vol. 101, pp. 589-93 (1976).

Mulligan, B.O. – 'Maples in the North Western U.S.A.', I.D.S.Y.B. 1970, pp. 13-19.

Murray, Edward A. – The author, a leading authority on the genus, has published numerous notes, keys and new combinations in his cyclostyled publication Kalmia.

Ogata, KenA Dendrological Study on the Japanese Aceraceae . . . Inst. For. Bot., Univ. of Tokyo (1965).

Vertrees, J.D. – Japanese Maples. Timber Press, Forest Grove, Oregon, USA (1978). See further under A. palmatum.


A site produced by the International Dendrology Society.

For copyright and licence information, see the Licence page.

To contact the editors: