SWAMP MAPLE (Acer Rubrum)

River-Lab 5 Guide Manual

SWAMP MAPLE (Acer rubrum)

Also known as red maple.

Swamp maples increase basin productivity by holding and enriching soil, by shading streams, and by providing actual living quarters for several kinds of animals.

The swamp maple is a medium-to-large tree (30-90 feet tall) that grows in the moist soil of floodplains, wetlands, and the banks of streams. Because the soil of its habitat is moist, the roots of the swamp maple do not grow deep, but are shallow and far-spreading. This shallow root crown makes the swamp maple a good soil holder, preventing erosion and excess silt in the river and estuary. This maple’s soil-holding capacity is often magnified by the fact that these trees multiply quickly, often taking over large areas of floodplain. Swamp maples also produce an impressive amount of material, in the form of branches, twigs, buds, etc., which, with unsprouted seed and other reproductive structures, fall onto the ground to decompose and enrich the surrounding soil or water.

Swamp maple trees also add to productivity by providing or maintaining habitats. Where limbs have fallen off, large, mature maples often develop cavities for nesting raccoons, squirrels, opossums, and birds. The large size attained by many of these trees often provides significant shade. This contribution keeps a stream cool and, therefore, as full as possible of oxygen, maintaining a large variety of aquatic life.

The shape of the swamp maple’s dull green leaves (2 1/2 – 6 inches long) generally resembles the sugar maple’s. However, the swamp maple’s leaf edges are saw-toothed and its leaf undersides are silvery. The stalks that hold the leaves can be reddish, as are twigs and reproductive parts such as buds, flowers, and fruits.

River-Lab 5 Guide Manual

SWAMP MAPLE, cont’d

Although in rare cases they can be monoecious, swamp maples are commonly dioecious. Male swamp maples produce thousands of deep red buds in early spring. When the buds open, tiny reddish flowers hang down in clusters on slender stems. As the male flowers mature, the anthers burst with yellow pollen grains. This combination of colors makes the flower appear orange from a distance. Once the pollen has blown away, the red flowers will fall, often carpeting the ground under the tree. The fallen male flowers become one of this plant’s enrichments to the floodplain soil or to the adjacent stream and its estuarine area.

The female flowers, also red, are usually on a separate tree. Since there is no yellow pollen, trees with female flowers appear dark red throughout the entire flowering season, from March to May. The female flowers have long sticky stigmas that reach out to catch pollen. The pistil of each flower has two egg cells. If fertilized by pollen, the eggs will grow into seeds. The ovary grows into a fruit around the two seeds and produces a little “wing” for each seed. The two winged seeds remain paired and attached to the tree throughout the summer.

In the fall, the winged seeds fall from the tree, sometimes breaking into single seed-and-wing halves. Strong fall winds may carry seeds as far as thirty miles, although most land nearby. The following spring, if conditions are right, a seed may sprout, producing a new valuable contributor to the basin system.