3. Acer rubrum L. (red maple)
c–f; Map 806
monoecious or dioecious, small to medium trees to 15 m tall with usually
spreading branches, the bark of young trees smooth and gray, eventually
becoming dark gray to brown and separated into long thin plates or ridges on
older trees. Twigs red and shiny, the winter buds ovate, bluntly pointed at the
tip, with 4–10 overlapping scales. Leaf blades 5–12 cm long,
broadly triangular-ovate to nearly semicircular in outline, the undersurface
lighter than the green to dark green upper surface and often strongly
white-glaucous, glabrous or hairy, with 3 or 5 main lobes, these tapered to
sharply pointed tips and with the sinuses angled or V-shaped, the lateral lobes
cut 1/4–1/2 of the way to the base, the central lobe shorter than to
slightly longer than the lateral ones and broadest at or just above the base,
the margins irregularly toothed (sometimes appearing doubly toothed).
Inflorescences produced before the leaves, dense clusters from lateral buds
along the branches, the flowers sessile or nearly so (the stalks elongating
greatly after flowering as the fruits mature). Calyces 1.4–2.2 mm long,
the sepals fused only at the very base, the 4 or 5 lobes oblong-elliptic,
rounded at the tips, red to purplish red, glabrous, the margins not scarious.
Petals 4 or 5, 1.6–2.4 mm long, narrowly oblong to linear, orangish red
to purplish red. Staminate flowers with 5–8 stamens inserted on the
margin of a nectar disk. Pistillate flowers with the ovary glabrous. Fruits
dispersing mostly after the leaves are mature, the samaras 2–4 cm long,
glabrous, the wings 1.5–3.0(–4.0) cm long, narrowly spreading,
sometimes appearing parallel or nearly so. 2n=78, 91, 104.
common in the Ozark, Ozark Border, and Mississippi Lowlands Divisions (eastern U.S. west to Illinois,
Missouri, and Texas;
Swamps, bottomland forests, mesic to dry upland forests, sinkhole ponds, banks
of streams, and ledges of bluffs.
Acer rubrum has been considered a minor component of
most forest ecosystems in which it occurs. However, Abrams (1998) has
documented an explosive increase in the abundance of this species throughout
much of its range during the past several decades that is analogous to the
situation apparent in Missouri
for A. saccharum. Abrams attributed this to an opportunistic increase of
the species resulting from the cumulative effects of land management patterns
in the region, including logging practices, land clearing for agriculture,
diseases of other forest trees, and fire suppression.
In addition to
the use of its wood for veneers, implements, furniture construction, and pulp
for papermaking, as well as the use of its sap as a low-grade substitute for
that of sugar maple in syrup production, red maple has also been used
historically as a source of tannins for ink production, and an extract of the
bark was used for preparing reddish brown and black dyes (Steyermark, 1963).
The leaves turn a bright crimson to orangish red color in the autumn and the
species is cultivated as an ornamental for its foliage. The species is highly
variable in leaf size, shape, and coloration. Some forms with 3-lobed leaves
have been segregated as var. trilobum, but as noted by Steyermark, there
is no correlation between this character and others involving fruit size and
leaf pubescence. In Missouri,
two ecologically distinctive but morphologically overlapping varieties may be
recognized. Plants in flower (prior to the development of leaves) cannot be
separated into varieties based on morphology, although the habitat in which a
tree is growing may provide clues, as var. drummondii is unknown from
upland sites in Missouri.