Black (& pale) swallow-wort are voracious vines that wrap around - or strangle - other plants as well as themselves - thus giving them the lovely name of "dog-strangling vine."
Pale and black swallow-wort look very similar when not in flower. Both species have long, oval, opposite leaves that are green and waxy, measuring about 3-4 inches long by 2-3 inches wide. The leaves of pale swallow-wort tend to be a slightly lighter shade of green than black swallow-wort.
Flowers of both species are small and star-like. Pale swallow-wort has a pink to maroon flower with petals that have a narrow base, whereas black swallow-wort flowers are a deep purple-black and have petals with a wider base.
However, during the month of August, flowers are no longer this plant’s key ID feature. Instead. you’ll be looking for their long, slender seed pods that kind of resemble string beans on a vine.
In terms of habitat, black and pale swallow-wort tolerate a variety of ...more ↓
Black (& pale) swallow-wort are voracious vines that wrap around - or strangle - other plants as well as themselves - thus giving them the lovely name of "dog-strangling vine."
Pale and black swallow-wort look very similar when not in flower. Both species have long, oval, opposite leaves that are green and waxy, measuring about 3-4 inches long by 2-3 inches wide. The leaves of pale swallow-wort tend to be a slightly lighter shade of green than black swallow-wort.
Flowers of both species are small and star-like. Pale swallow-wort has a pink to maroon flower with petals that have a narrow base, whereas black swallow-wort flowers are a deep purple-black and have petals with a wider base.
However, during the month of August, flowers are no longer this plant’s key ID feature. Instead. you’ll be looking for their long, slender seed pods that kind of resemble string beans on a vine.
In terms of habitat, black and pale swallow-wort tolerate a variety of soils and environmental conditions. Swallow-wort favors full sun but may thrive in semi-shaded to densely shaded areas, as seen here. These species are disturbance-and drought-tolerant and can quickly spread once established.
Furthermore, black and pale swallow-wort have similar flowers to milkweed, the primary host plant for monarch butterflies. The swallow-worts have that same star-shaped flower that monarchs often mistake for milkweed when they lay their eggs, but when the eggs hatch there's nothing to eat.
Even if the butterflies don’t lay their eggs on this plant, swallow-wort can easily outcompete the native species once they have a stronghold in an area. Just look at this mono-crop in this shaded woodland. A square meter stand of swallow-wort is capable of producing 1,000-2,000 seeds per year, which are then dispersed by wind. It also releases chemicals into the soil that prohibit the growth of other species!
Identification is the first step toward plant control. With your help, we can take steps to manage and control this invasive species!
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Invasives Strike Force EcoQuest
