Cottonwood trees are often recognized by the distinctive “cotton-like” material they release. This guide explores their physical attributes, including their structure, leaves, bark, and the famous “cotton” they produce.
Overall Tree Characteristics
Cottonwood trees are substantial deciduous trees, commonly growing to 70-100 feet tall, with some species reaching over 150 feet. They can spread 50-75 feet wide, forming a broad or irregularly rounded crown. Their rapid growth rate, sometimes adding 5-8 feet in height annually, contributes to their presence.
These trees typically feature a straight trunk that can exceed 4 feet in diameter in mature specimens. Cottonwoods thrive in moist environments, frequently found along riverbanks, streams, and floodplains. They require full sun and are intolerant of shade, often establishing themselves in open areas.
Leaves and Bark
Cottonwood leaves are an identifying feature, typically triangular or heart-shaped with coarsely toothed edges. These leaves usually measure 3 to 6 inches long and are nearly as wide, appearing bright green on the upper surface and often paler underneath. Their flattened petiole, or leaf stalk, allows the leaves to flutter and rustle with the slightest breeze, creating a distinctive shimmering effect. In autumn, the foliage typically transforms into a golden yellow.
The bark of a cottonwood tree changes with age. Young trees display smooth, yellowish-green or silvery-white bark. As the tree matures, its bark transitions to a dark gray or brownish-gray, becoming deeply furrowed with prominent ridges. Older specimens may even exhibit a diamond-like pattern in their thick, ridged bark.
The “Cotton” and Its Source
The most recognizable feature of cottonwood trees is the “cotton” that fills the air during late spring and early summer. This fluffy material originates from female cottonwood trees, which are dioecious (male and female flowers grow on separate trees). In early spring, both male and female trees produce catkins, which are cylindrical clusters of small flowers. Male catkins are often reddish or yellow, while female catkins are typically green.
Following pollination, the female catkins develop into small, green seed capsules. These capsules split open, usually from late May through June, to release tiny seeds. Each seed is attached to a mass of soft, white, cotton-like fibers. This fluffy material enables the seeds to be carried long distances by the wind, sometimes appearing like snow falling in summer as they accumulate on surfaces.