Willow Weave Fence. Photo credit: Si Griffiths CC BY-SA 3.0
The Herb Society of America chooses a Notable Native Plant every year. Their definition of a native herb refers to “mostly seed-bearing, generally fleshy annuals, biennials, and perennials, aromatic or useful shrubs, vines, and trees that grew naturally in this country, without the influence, accidental or intentional, of man, prior to European settlement."
For 2018, the herb society has chosen willow (Salix spp.) also known as sallow or osier. There are approximately 107 species and subspecies native to the United States and Canada.
Willows have varying shapes; there are upright shrubs and trees and those with weeping habits. Some cultivars are bred to have colored stems which may be yellow, black or red. Leaf shapes come in a wide variety as well, their shapes may be rounded to long and slender, and the colors vary from deep to silvery green. Some of the narrow leaved shrub species are called osier while the broader leaved species are referred to as sallow.
Willow trees grow well in areas with moist soil and they are used to control erosion along streambanks and waterways where their roots reach into the soil and provide stabilization. They are often used to identify wetlands. This leads to a caution about planting willows near sewers and water pipes as the roots will move into these area and could cause problems.
The willow is important to wildlife. The tender new leaves are eaten by grazing animals and some birds, especially hummingbirds, use the fuzzy catkins to line their nests.
The well-known pussy willow (Salix discolor) is commonly grown for use by the floral design industry. It is a native U.S. tree growing 6 to15’ tall depending on variety and is recommended for zones 4-8. Pussy willows have male and female catkins developing in early to mid-spring on separate plants. These catkins consist of tiny, multiple flowers pollinated by early season bees, flies, and wasps. The blooms are a valuable food source for wildlife and are one of the first spring nectar sources attracting insects. The insects, in turn, provide a smorgasbord for songbirds, especially chickadees and goldfinches.
Dr. Douglas Tallamy, Professor of Entomology and Wildlife Ecology at the University of Delaware reports that the Salix spp. supports 455 butterfly and moth species. Willows are larval plants for the mourning cloak, viceroy, and red-spotted purple butterflies.
The bebb willow (Salix bebbiana) is the most commonly used diamond willow and features colorful diamond-shaped patterns inside its stems making it a favorite among woodcarvers. This native species is drought tolerant once established and grows 10-30’ tall.
One of the most common willows is the weeping willow (Salix babylonica), a non-native introduced from northern China. It reaches 35-50’ and is hardy in Zones 4-8.
Different cultures have used parts of willow trees such as bark and leaves for medicinal purposes, especially for pain relief. In the 1800’s, scientists found the compound salicin in the bark which led to the development of aspirin.
Various Native Americans tribes historically used willow to make many everyday items. The wood, bark, and branches were used to make furniture, baskets, drums, as well as moose calls and snowshoe frames.
The wood is flexible enough to be bent once it has been soaked in water and is used to construct trellises and plant supports. Wattle fences made from willow branches are often seen in colonial and English gardens.
The environmental and economic benefits of willows are being studied at The College of Environmental Science and Forestry, State University of New York as part of its Willow Biomass Project. Their project brochure states that "...willow biomass crops are planted once and harvested every three to four years, up to seven times. Improvements to the willow production system are increasing potential returns for landowners.
Woody biomass from shrub willow can be converted into different forms of renewable energy and environmentally friendly products that offset the use of non-renewable fossil fuels.”
The Oregon State University Extension Service notes that a rooting tonic can be made from small willow branches. While this may be useful, the process is involved and not necessarily the best way to root cuttings.
Since there are so many species and varieties of willows, home gardeners should consider which will fit in their landscape. They can be an important addition to creating areas of biodiversity in gardens providing food sources for pollinators and insects for the birds.