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Black Swallowwort
Cynanchum louiseae (Cynanchum nigrum, Vincetoxicum nigrum)

Black swallowwort was introduced to this country as a garden plant. It is now a common weed, both in gardens and in wild areas. A related plant, pale swallowwort, grows in the same habitats. The plants can be distinguished by the flowers. Black swallowwort flowers are always a very dark purple, nearly black. The petals are covered with fine white hairs, and the petal length is about equal to the width. Pale swallowwort flowers range from a light brownish color to dark red, but they are never nearly black. Pale swallowwort petals are hairless, and they are about twice as long as they are wide.

Black swallowwort is an invasive weed that threatens native plant habitats. More on this topic from Invasive Plant Atlas of New England.

• Family: Milkweed (Asclepiadaceae)
• Habitat: roadsides, fields, edges of woods, rocky areas
• Height: 3-6 feet
• Flower size: 1/8 inch across
• Flower color: dark purple-brown
• Flowering time: June to September
• Origin: Europe

next green/brown flower
next in milkweed family
Cynanchum louiseae
Cynanchum louiseae
The petals of black swallowwort are covered with fine white hairs.

Last updated June 20, 2006. © 2005 Connecticut Botanical Society. All rights reserved.