Thursday, November 6, 2014

Salix nigra

Common Names: black willow
Family: Salicaceae (willow Family)

Black willow is typically a tree, but is often shrubby with multiple trunks, and often forms thickets. It can reach 65 ft (20 m) in height, but often assumes a leaning posture. Leaves are alternate, variable in size, lance shaped, and generally three times longer than wide. The tops and bottoms of the leaves are green and usually hairless. Compare this to the similar and closely related Carolina willow (S. caroliniana), which has whitish-glaucus leaf undersides that are often sparsely pubescent. Male and female flowers (catkins) are on separate plants, and come out before the leaves in early spring. The seeds are tiny and sail on the wind with long silky white hairs.

Salix nigra occurs naturally from New Brunswick west to Minnesota and thence southward to Georgia and northern Florida. Black willow grows in wetlands and along stream banks and the shores of ponds and lakes. It frequently colonizes disturbed sites, and often is very abundant where it occurs. The related Carolina willow (S. caroliniana) has a more southern distribution, ranging from Maryland west to Indiana and south to Texas, throughout Florida, and in Cuba.

Light: Black willow usually grows in full sun, but can tolerate partial shade.
Moisture: Black willow grows in wetlands and likes a soil that never dries out. It can tolerate periodic flooding.

Propagation: Willows are easy to propagate from cuttings and new plants can be started by merely breaking off a branch and inserting it in damp ground.

If your landscape has an area that stays wet a lot, chances are you already have either black willow or the related Carolina willow growing there. The airborne seeds have a way of finding wet spots wherever they are. Willows are valuable for erosion control and when growing along stream banks their tenacious root systems, which may dwarf the above-ground part of the tree, serve to hold the soil in place. The upright catkins are attractive in spring (especially the male ones), and birds use the cottony seed sails for nesting material.
There are more than 300 species of Salix in the world, with most occurring in the Northern Hemisphere. The inner bark of willows is aromatic and astringent and was the original source for salicylic acid, which is the active ingredient in aspirin. The Ancient Greeks, as well as peoples from the Middle East and Native Americans knew the value of willow bark for treating aches, fevers and inflammation. Today salicylic acid and aspirin are manufactured synthetically.

There are about seven species of Salix occurring naturally in wetlands in the southeastern U.S. One (S. floridana) is very rare and grows only along certain spring runs in central and northern Florida. The weeping willow (S. babylonica), so popular in home landscapes, has escaped cultivation and grows wild in many parts of the U.S.

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