Acer rubrum Seeds | Red Maple
LATIN NAME: Acer rubrum
COMMON NAME: Red Maple
Plant Profile
Long before anything else in an eastern North American wood has thought about spring, the red maples have done the important part. In late winter the bare crown of Acer rubrum fills with dense clusters of small red flowers, the female with paired stigmas and the male heavy with stamens, and the tree takes on a red haze visible right across a valley. The leaves have not begun to move.
The leaf usually carries three main lobes and sometimes two smaller ones below, with irregular teeth along the margin, a pale and often glaucous underside and a red leaf stalk that gives the tree away in midsummer when nothing else is red. The same colour runs through the flowers, young twigs, buds and samaras, which is why the tree can be identified from a moving car in April.
Red maple has increased greatly across eastern forests over the last century. Fire suppression, abandoned farmland, partial cutting and the loss of chestnut all removed competitors or opened the canopy, and red maple colonises well: it seeds young and heavily, grows fast and tolerates enough shade to establish beneath a canopy and wait. Foresters now treat it as a problem in oak stands.
Maples are routinely multiplied in vitro for clonal forestry and for named cultivars, using axillary shoot culture to bulk up a selected genotype and, in several species, somatic embryogenesis to produce large numbers of plantlets. For red maple the technique is most useful where a colour selection must be reproduced exactly, since seedlings vary. The plantlets need shading and humid air before full sun.
Science & Biotechnology
The red of autumn is anthocyanin, built in the leaf during the last weeks of the season rather than merely revealed as chlorophyll breaks down. Bright days with cool nights raise sugar levels in the leaf and favour synthesis, which is why a fine autumn gives a better display than a wet, cloudy one. The same pigment colours the spring flowers and the young samaras.
Uses & Benefits
In wet ground the species copes with low oxygen around the roots better than most hardwoods, keeping water moving while neighbouring trees shut down. Its wood is less dense and softer than sugar maple, a fair trade for fast growth on poor sites, and that lighter timber is what places it in the soft maple group. It also re-sprouts vigorously from a cut stump.
Red maple timber is pale and hard enough for most uses but distinctly softer and less figured than sugar maple, and the trade groups it with silver maple as soft maple. It goes into furniture frames, kitchen cabinets, joinery, flooring, pallets and pulp, and it is the standard wood behind painted furniture because it takes paint evenly and resists denting.
Red maple’s autumn display runs from dull yellow through orange to deep scarlet, and that variation is the basis of the nursery trade in named selections, among them the widely planted colour forms ‘October Glory’ and ‘Red Sunset’. Breeders also look for a straight trunk, narrow branch angles and a crown that resists storm damage, because the species can split badly at a narrow fork.
Growing from Seed
Because it flowers early, red maple ripens its fruit early. The paired samaras, red when young and brown as they harden, are shed in late spring or early summer, roughly as the leaves finish their first flush. Most maples scatter their keys in autumn, so a winged crop in early summer is a departure, and the narrow angle between the two wings gives the falling pair its twist.
Few eastern trees occupy so much ground. Red maple grows in flooded swamps, where it tolerates standing water for long periods, and it also grows on dry ridgetops in thin upland soil, as well as everywhere between on seepages, wet hollows and old fields. That breadth is why it is called swamp maple in one county and soft maple in the next.
Red maple samaras are short-lived once dry, so sow them while fresh, soon after the winged crop falls. Scatter the seed over a bed of sandy loam and leaf mould, cover it very lightly, and keep the surface damp and the bed shaded. Thin the seedlings when they have two pairs of true leaves, so the plants stand about a hand apart.
Our Take
Red maple rewards the impatient gardener, since fresh seed and a damp bed give you a wood of your own within a few seasons, and the tree grows almost anywhere that is not bone dry. For the wetter end of the group see silver maple, for the timber comparison see sugar maple, and for a small garden see field maple.
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