Bigleaf Maple (Acer macrophyllum)
Bigleaf Maples are one of the characteristic large trees in Pacific Northwest forests. They grow best and biggest in wet lowland forests west of the Cascades, but they can also be found on dry hillsides along the Columbia River gorge. The largest known individual, growing near Jewell, Oregon, was thought to be over 200 years old. It was 31.4 m tall, with a canopy spread of 34 m and a trunk 3.5 m in diameter. Sadly, it was so weakened by internal rot that it crashed to the ground during a wind storm in March 2011.
The leaves of Bigleaf Maple, as the name implies, are the largest of maple leaves, measuring up to 30 cm across. They feature five large lobes with smaller lobes along them. Unlike many other maples, they do not flame brilliantly in autumn, but they can still be picked out by their dull yellow to light brown leaves at that time, and a large stand can be somewhat showy.
The flowers appear before the leaves develop, hanging down in cylindrical clusters from the twigs in spring.. They are small (about 3 mm across) and pale green, with prominent stamens. The fruits are typical maple samaras, light brown with 3-6 cm “wings” spread in a V shape and carrying a single seed up to 1.5 cm in diameter. During a windy day in autumn, the air can be full of these samaras whirling past on their way to the ground, where, if conditions are right, a tiny maple seedling may pop up the next spring.
These seedlings can be common, but they are probably doomed to a short life if a light gap doesn’t open up to allow them sufficient light for long-term photosynthesis. Extensive browsing of these seedlings by Black-tailed Deer makes for a very short life for most of them. Nonetheless, if given the chance, the seedlings can grow to 3 m tall in a single year, and they may outcompete conifers on tree plantations.
Bigleaf Maple has rough bark with longitudinal ridges, and it supports more epiphytes than any other tree in the region. The trunk can be covered by moss and lichens and, most prominently, Licorice Ferns. Plants can become so dense on the trunk that they produce their own soil from all the particulate matter trapped there, and the tree then does the amazing thing of producing tiny roots, called canopy roots, that burrow into this material and extract nutrients just as the main soil roots do.
Bigleaf Maples are the only maple large enough to be used for lumber in the Pacific Northwest. The moderately hard wood has been much used for veneer in furniture production. Among some Native American tribes, the tree was known as “paddle tree,” as it was apparently the perfect wood from which to make canoe paddles.