Botanist says stealthy invasive willow putting local rare plants at risk
Durham , NH —A government botanist in New Hampshire said recently that a little noticed, opportunistic willow seen across Massachusetts and Rhode Island is a growing problem and should be regarded as a highly invasive plant species.
Thomas Rawinski, a botanist with the USDA Forest Service, said the large gray willow, or Salix cinerea, is a serious threat to rare plant species that are being displaced by the willow. One of its best defenses to date has been stealth, said Rawinski. It looks very similar to some of our native willows. Botanists assumed for years that the European species was one of the natives.
The large gray willow was planted as an ornamental nearly 100 years ago and has since escaped cultivation by way of its windborne seeds. It colonized coastal plain pond shores, dune swales and other wetland habitats. It grows to the size of a small tree and its shade degrades the habitat for many rare plants such as Plymouth gentian, rose coreopsis, hyssop hedge-nettle and slender marsh pink. Some rare dragonflies and damselflies are also adversely affected. In the dune swales of Sandy Neck in Barnstable , Mass. , the willow is crowding out wild cranberries.
The large gray willow is also causing problems as far away as New Zealand and Australia, where it is regarded as a major weed.
“The introduction of non-native species across the world is a serious negative consequence of globalization,” said Rawinski. “The distribution of the willow in New England and New York is not yet fully known, so additional searching is needed. However, the most serious infestations in Massachusetts are already being targeted for control.”
Rawinski noted that some of the willows represent the subspecies oleifolia. Certain willow experts consider this subspecies to be a distinct species unto itself, and refer to it as rusty willow (Salix atrocinerea).