The Super Genus Salix: More Than Just the Weeping Willow

March 2018

The appearance of velvety pussy willow catkins in our wetlands hails the beginning of the end of winter in New England. While largely known for their decorative value, the pussy willow (Salix discolor) and its fellow members of the genus Salix, are also ecological dynamos. They are important colonizers of disturbed areas, especially riverbanks and wet areas after floods or fires. And they are a vital source of food for all kinds of wildlife, in particular as a host plant for many, many types of caterpillars.

The most recognizable willow varieties, such as the weeping willow (Salix babylonica) and the florist's willow (Salix caprea, the pussy willow branches sold in shops), are actually native to Europe or Asia, but there are nearly 40 species of willows native to New England alone. Most willow species are actually shrubs or multi-stemmed small trees that grow in dense stands, not the elegant massive-trunked trees we typically associate with the name "willow" (the black willow, Salix nigra, is the only native species that reaches great girth). Willows are fast-growing, making them highly valuable for wetland restorations, and most of the native willow shrubs available commercially are grown for this purpose. This growth habit, along with flexible and brittle wood that results from it, has kept willow shrubs from becoming popular as horticultural plants. But a gardener creating a landscape with biodiversity in mind should not forget about willows.

In Bringing Nature Home, Doug Tallamy lists Salix as the second most important Lepidopteran host genus, after oaks.  Willows support many charismatic butterflies, including mourning cloaks, viceroys, commas, red-spotted purples, as well as sphinx moths. Wood-boring beetle larvae and other insects love soft willow wood, as do the woodpeckers that forage in the trunks for tasty insect treats. Delicate young willow twigs also provide important forage for mammals during the winter. A little something for everyone! If you have a sunny, wet spot where you need a screen, and plenty of room to spread, give the willows a chance!