Willows are deciduous, flowering trees and shrubs belonging to the two main genera Salix and Populus, members of the Willow Family, Salicaceae. There are over 57 genera worldwide, concentrated mainly in temperate and arctic regions of the northern hemisphere. Members of the Willow Family have simple alternate leaves which appear in the springtime and become bright red, orange, and yellow before falling off in autumn. Their flowers are catkins, with most species being dioecious, male and female flowers borne on separate individuals. The fruit of Salicaceae species are capsules opening in 2-4 parts, containing many tiny seeds with cotton-like hairs. Willows, Poplars, and Cottonwoods are often midsized trees, with heights on the scale of 10-80 feet. Their bark can vary from gray to brown, becoming furrowed in older individuals. Willows are strongly associated with riparian habitats, as they are most commonly found in wet soils near creek systems, and may be found in dense stands on riverbanks in healthy riparian ecosystems. Other Willows and Cottonwoods may be found further from rivers with large, spreading crowns.
Salix – Willows
The Genus Salix contains more than 300 species of deciduous trees and shrubs worldwide. Willow species have linear leaves, which are simple, alternate, and entire. Depending on species, Willow leaves can be less than 1 to more than 6 inches in length, less than 1 inch wide. Willow flowers form in early spring at the same time or before the leaves appear. Its flowers are catkins generally 1-2” in length, borne on the end of leafy twigs, often with white or yellow hairs. Female catkins are borne on separate plants, and are a similar size to male catkins. Since Willow species are dioecious, cross fertilization is possible creating hybrid varieties unique to a specific area. Willow fruits are capsules which can also be hairy. Willow bark and leaves contain salicylic acid, which is a historical cure for pain. This compound has since been isolated by western science and is an active ingredient of Aspirin.
One common species of Willow in Lake of the Pines is Sandbar Willow, Salix exigua, which is found growing naturally along our creek pond banks. In its mature state, it reaches heights of 10-25 feet and grows in dense colonies, as it spreads laterally by basal shoots. It has male and female catkins of about 3 inches in length, with capsules containing many seeds embedded in shiny white silk.
Another well known variety is Weeping Willow, Salix babylonica, is a Chinese cultivar. Weeping Willow has a large broad crown of drooping branches. It has 2-5” leaves, which are ½” wide, lance shaped, dark green above and whitish below. It has a thick gray bark, deeply furrowed, 2 or more feet in diameter, and growing to heights of around 40 feet. Weeping willow is often found at the edges of ponds in wet soils, one can be seen across the pond at the front gate of Lake of the Pines.
Populus – Cottonwoods
The other major genus of trees found in our area belonging to the Willow Family is Populus, which contains Cottonwoods, Poplars, and Aspens. Like Salix, Populus species have deciduous leaves, although their shape is broadly triangular compared to the linear Willow leaves. Populus species have male and female catkins which appear in early spring and borne on separate trees. Fruits are egg-shaped capsules which split into three parts releasing many cottony seeds.
Fremont’s or Western Cottonwood, Populus fremontii is a large broad crowned tree, with thick furrowed gray bark, growing to 40-80’ in height. It has 2-3” broad leaves with finely toothed margins, which are green during spring and summer becoming bright yellow by autumn. It is commonly found growing near river valley bottoms in the Sierra Nevada Mountains, and can be seen around Lake of the Pines. Quaking Aspen, Populus tremuloides, is found growing in stands in wet soils at higher elevations of Tahoe National Forest, creating unique habitats.
