Anatomy of the Bigleaf Maple:
This tree is made up of many different parts, including:
The bark: When the tree is young, the bark is a brownish color with a smooth layer. As the tree matures, it becomes a darker brown, and furrows and ridges begin to appear on the outer layer of the bark.
The twig: The twig is smooth, round, and commonly a pale green in color. In the fall, it turns a bright green red, and finally grayish brown. There are two buds on opposite sides of a main bud, which are bigger than the other two, and these buds have 3 or 4 scales.
The roots: The roots of the tree are often shallow but widespread; this type of root system make it easier for the plant to grow shallow or saturated soils.
The leaf: The leaf is a simple, deciduous leaf, and it is between 6 to 12 inches in diameter, but sometimes much larger. It is also palmately lobed, which means the leaf has five “arms.” The leaf is dark green on the top, and light green on the bottom. When crushed or cut, the petiole discharges a white sap.
The flower: The flowers are monoecious. The flowers are a small, and are often yellow. They bloom in long racemes.
The fruit: The fruit are double samaras. The wings on the samaras are 1.5 to 2 inches long, and occur at acute angles. The head of the seed appears to be hairy. When the seed is mature, it turns a tan color.
Reproductive parts of a bigleaf maple.
The Bigleaf maple’s main form of reproduction is sexually, but it can also reproduce vegetatively. Maple is polygamous, bearing both male flowers and perfect flowers in one cylindrical raceme. The flowers appear before the leaves in early spring. The greenish-yellow flowers are pollinated by insects within 2 to 4 weeks after bud-burst. The flowers on the bigleaf maple start to show up when the tree is about 10 years old, but trees growing in an open area start to produce flowers earlier and also produce more flowers. These flowers are pollinated by insects, and small animals may also help disperse the seeds. The seed can only germinate for a couple months. If they do not, they will start to decay near the end of the winter months. Even indoors, the seed will not last for more than a few months at low to room temperature. Another factor that reduces germination rates is the consumption of the seeds by rodents. One year old seedlings in Oregon were about 2.3-3 inches in height. This plant grows more slowly when it is grown in the shade of another tree, especially Douglas-firs. This tree can also regrow from the root if it is cut down or killed.
Bigleaf maple seeds are borne in pubescent, double samaras with wings from 1.4 to 2 inches long. Seeds are triangular or oval in shape and 0.16 to 0.47 in. long. There are from 2700 to 4000 seeds/lb. Seeds ripen early in September and October, and are dispersed by the wind from October through January. Many seeds may remain on trees during this period.