The willows are the largest group of trees native to North America. Today, we have close to 100 true species and approximately 50 hybrids. Here, in Pennsylvania (according to my tree book), we have two introduced willow trees; five native species and 28 species of shrubs. There are 300 to 400 species worldwide.
During Colonial Times, the weeping willow tree was introduced from China. In all seasons, the weeping willow tree is identified by its long and graceful drooping branchlets. The weeping willow tree’s scientific name is Salix babylon, with Salix being the classical Latin name of the willow and with Babylon being the specific name meaning, of Babylon. This tree was thought to have been the willow at Babylon where the exiled Jews sat down and wept (Psalm 137, 1- 2).
The black willow, which is the largest of our native willow trees, is the large willow seen growing in our bottom lands and along stream banks. The diameter of the trunk sometimes reaches three feet. The crooked trunks often grow in clumps and are usually inclined.
The buds of the weeping willow tree are a work of art. They are about one half of an inch long, pointed, brownish in color and closely hug the twig. The buds are covered with a wax that makes them waterproof. Although most buds open by using either scales, joints or hinges; however, this is not so with the willow bud. When ready to open the bud’s waxy seal explodes as though it was made of glass. The willow buds are among the first buds to burst open in the spring, exposing small green leaves to the sun, even when snow is covering the ground.
The willow tree, which has no commercial value, is considered a shade tree. It is a fast growing tree and is easily damaged by storms.
The male catkins will become yellow flowers, and the female flowers will show green. The bees are attracted to the male flowers because of their yellow color and to the female flowers because of their fragrant scent.
In early summer, the female capsules will split open and release a large amount of seeds to the wind. Each seed is attached to a silver filament, which is picked up by the wind and often carried long distances. At this time, seeds are primed and ready to grow. If conditions are favorable, germination will begin immediately. Willow seeds can only retain their ability to germinate for a few days; therefore, the tree needs the following backup system: During a storm, a brittle green branch breaks off and falls into a stream and floats away. At some point, the branch will come to rest, and when it does, the twig will send down roots. Presto, a new tree begins to grow.
Most trees obtain the oxygen they need to survive from their roots. This is because there is oxygen between the soil grains. Willows are one of the few deciduous trees that can flourish with its roots in water soaked soil, having little or no oxygen. Experiments have shown that the willow tree takes in oxygen through its twig tips and delivers it to the root tips in the water-soaked soil. This is only a meager supply of oxygen but enough to keep the root hairs operating and enough oxygen to keep the tree alive and growing. (The bald cypress is another tree that has this strange type of oxygen delivery system.)
The willows are used as food by the larvae of the mourning cloak butterfly and ants come to the willows to collect the aphids’ honeydew. Willow branches are pliable and are often used in making baskets.
Willow trees produce an abundance of milky sap, which contains a substance known as salicylic acid. In 1763, Edward Stone isolated this acid for use as a medicine; however, the acid caused too much stomach upset to be used. Then, in 1897, a chemist, Felix Hoffman, created a synthetic version, which was gentle on the stomach. Hoffman’s company, Bayer, produced his discovery as the first aspirin.
Black willow roots, which are very bitter, have been used as a substitute for quinine in the past. Black willow was used by various Native American tribes to make baskets and as a treatment for fever, headache and coughs.
The next time you take a few pills to relieve the pain of a throbbing headache, say a thank you to one of our interesting tree groups, the willows.