Acer rubrum L.

TSO logo

Sponsor

Kindly sponsored by
a member of the International Dendrology Society

Credits

Dan Crowley (2021)

Recommended citation
Crowley, D. (2021), 'Acer rubrum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-rubrum/). Accessed 2024-02-22.

Genus

Common Names

  • Red Maple

Other taxa in genus

Glossary

cordate
Heart-shaped (i.e. with two equal lobes at the base).
cuneate
Wedge-shaped.
glabrous
Lacking hairs smooth. glabrescent Becoming hairless.
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
variety
(var.) Taxonomic rank (varietas) grouping variants of a species with relatively minor differentiation in a few characters but occurring as recognisable populations. Often loosely used for rare minor variants more usefully ranked as forms.

Credits

Dan Crowley (2021)

Recommended citation
Crowley, D. (2021), 'Acer rubrum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-rubrum/). Accessed 2024-02-22.

A deciduous tree to 28 m. Bark grey, smooth when young, turning darker and fissuring longitudinally with age, sometimes developing ridges or plates. Branchlets slender, glabrous or white tomentose, greenish, turning red to reddish brown. Buds ovoid, with four to seven pairs of imbricate scales. Leaves broadly pentagonal in outline, chartaceous to coriaceous, base cordate to cuneate to rounded, unlobed or three to five (-nine) lobed, 5–18 × 2–10 cm, lobes apically acute, margins serrate or double serrate with acute teeth, upper surface light green, lower surface paler or glaucous, glabrous, pubescent or white tomentose; petiole 5–10 cm long, red or green, glabrous, pubescent or white tomentose, often grooved, broadest at base; autumn colours yellow to scarlet. Inflorescence axillary, fasciculate-umbellate, few flowered. Flowers red (rarely yellow), 5-merous, monoecious or dioecious, pedicels long and slender, sepals oblong, obtuse, petals linear to oblong, shorter than sepals, stamens five to eight, inserted in the middle or on outside of the nectar disc. Samaras 1.2 to 3 (–5 cm in var. drummondii) cm long, wings spreading erectly to acutely. Nutlets slightly convex. Flowering January to May, before unfolding leaves, fruiting in late spring to summer (Sargent 1965; (van Gelderen et al. 1994; Rushforth 1999; Lance 2004; Weakley 2012).

Distribution  Canada New Brunswick, Ontario, Québec United States Arkansas, Alabama, Connecticut, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Missouri, Mississippi, North Carolina, New Hampshire, New York, Oklahoma, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Vermont, Virginia, West Virginia, Wisconsin

Habitat Mixed deciduous forest and margins of boreal forests. It occurs on both dry and wet sites, along rivers and lakes, in marshes, swamps as well as on sandy plains, dunes and rocky, mountain slopes between 0 and 1370 m asl.

USDA Hardiness Zone 4-10

RHS Hardiness Rating H6

Awards Award of Merit

Conservation status Least concern (LC)

Taxonomic note (Weakley 2012) treats A. rubrum var. drummondii at specific rank, indicating that it is of hybrid origin derived from A. rubrum and A. saccharinum, though this interpretation is not widely accepted and its varietal status is followed here. This author also treats two varieties within A. rubrum: var. rubrum and var. trilobum. The two are separated by degrees of leaf size and lobing, the nominate variety with leaves usually with cordate bases, five lobes and 7–18 cm wide, while those of var. trilobum usually with cuneate to subcordate bases, unlobed to three lobed and 2–10 cm wide. However, intermediate leaf characters are found on plants in cultivation and thus, no attempt has been made to distinguish between the two here.

A deciduous tree, occasionally over 100 ft high in America, with a trunk up to 13 ft in girth; and over 70 ft high in England, forming a rounded head of branches; bark greyish; branchlets glabrous, except when quite young. Leaves three- or five-lobed (the lobes pointed and somewhat triangular, the middle one usually the longest), from 2 to 5 in. wide, and often longer than broad, coarsely and unevenly toothed; upper surface dark green, glabrous, lower one blue-white and more or less downy, especially along the veins. Flowers appearing in March and early April in dense clusters before the leaves, at the joints of the previous year’s wood, or on short spurs of still older wood, rich red, each flower on a reddish stalk at first quite short, but lengthening as the flower and fruit develop. Fruits on slender drooping stalks 2 to 3 in. long; wings about 34 in. long, 14 in. wide, dark dull red spreading at about 60°.

Native of eastern N. America, and already in cultivation in England by the middle of the seventeenth century. It is a handsome and fairly common tree. When the first edition of this work was published the largest in the country grew at Bagshot Park, Surrey, which measured 80 × 912 ft (1907); the tallest there now is 65 × 1012 ft (1960). At Westonbirt there is a specimen of 73 × 434 ft in Willesley Drive and two others in the collection approaching that size. At Wakehurst Place it is 65 × 612 ft (1966) and at Kew 52 × 534 ft (1960). The red maple is represented in the R.H.S. Gardens, Wisley, by an example 45 ft high, near the lake.

There is a considerable resemblance between this tree and A. saccharinum, and they are frequently confused. A. rubrum, however, is more compact and of slower growth; the leaves are not so much or so deeply cut, the down beneath them more fluffy, and the fruits are less than half as large. In the United States this maple produces most beautiful colour effects in autumn, the leaves turning scarlet and yellow. In this country it is not so good, but sometimes the leaves change to bright yellow, or dark brownish red, or occasionally red. It should be planted in a moist position.

From the Supplement (Vol. V)

specimens: Bagshot Park, Surrey/Berks., 70 × 1214 ft at 3 ft (1982); Wakehurst Place, Sussex, 42 × 714 ft (1981); Ashburnham Park, Sussex, 58 × 812 ft (1978); Melbury, Dorset, Pleasure Gardens, 50 × 812 ft and, Valley, 58 × 734 ft (1980); Trewidden, Cornwall, 56 × 914 ft at 3 ft (1979); St Fagans, Cardiff, a fine tree, 77 × 7 ft (1980); Powis Castle, Powys, 58 × 712 ft (1981).

† cv. ‘Scanlon’. – A selection giving fine autumn colour and with a conical crown that makes it suitable for confined spaces. It is one of the many ‘tailor-made’ trees bred by E. H. Scanlon and Associates at Olmsted Falls, Ohio, USA.

† cv. ‘October Glory’. – A selection for autumn colour, raised in the USA by the Princeton Nurseries.

Cultivars such as the above are preferable to seed-raised trees, which can be very disappointing if autumn colour was hoped for.

A. pycnanthum – This is now in cultivation and growing well.


A pycnanthum K. Koch

Synonyms
A. rubrum var. pycnanthum (K. Koch) Mak

A rare tree, found in wet places in the mountains of the northern part of the main island of Japan. It is a close ally of the American red maple, differing in the shallowly three-lobed leaves, which are glaucous and glabrous beneath; and in the almost erect fruit-wings. Probably not in cultivation in Britain.

'Columnare'

A pyramidal variety figured in Garden and Forest, 1894, p. 65, growing in private grounds at Flushing, New York, which was then 80 ft high. The figure is erroneously described as a form of sugar maple.

'October Glory'


'Sanguineum'

The original tree of this variety grew at the Jardin des Plantes, Paris. Its leaves are glaucous green beneath, somewhat more downy than in the type, the flowers brilliant red. The leaves are said to turn a rich red in the autumn but at Kew, where there is an example 55 ft high, they colour no better than in the type.

'Schlesingeri'

A clone selected in the United States for its brilliant autumn colour. It was found by Prof. Sargent in the grounds of a Mr Schlesinger and put into commerce in Europe by Späth’s nurseries in 1888.

var. drummondii (Hook. & Arn.) Sarg.

Synonyms
A. drummondii Hook & Arn

Differs in the downy character of the young shoots, leaf-stalks, and under-surface of the leaves. Fruit and flowers bright scarlet, the former larger than in ordinary A. rubrum. Native of Arkansas, Texas, and Louisiana.