Ontario Weeds: Dog-strangling vine
Excerpt from Publication 505, Ontario Weeds,
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Table of Contents
- Other Names
- General Description
- Stems and Roots
- Flowers and Fruit
- Similar Species
- Related Links
Name: Dog-strangling vine, Vincetoxicum
nigrum (L.) Moench,
Other Names: cynanque noir, Black swallow-wort, Cynanchum nigrum (L.) Pers.
Family: Milkweed Family (Asclepiadaceae)
General Description: Perennial, reproducing by seed and by spreading underground rhizomes.
Dog-strangling vine (A - plant; B - pairs of leaves and pairs of spreading seedpods).
Dog-strangling vine. A. Base of plant with flowering branch. B. Twining branches with 2 open seedpods.
Stems & Roots: Stem vine-like,
herbaceous or with woody base which overwinters successfully in
Ontario, 1-2m (3-6½ft) long, scrambling or climbing over
fences and other vegetation and often forming impenetrable masses.
Leaves opposite (2 per node), oval to oblong with rounded bases
and abruptly pointed tips.
Flowers & Fruit: Flowers purple-brown to dark purple, small, in small umbel-like clusters at tips of stems and upper branches; seedpods slender, 4-6cm (1½ -2¼in.) long, broadest near the base and long-tapered to a slender tip, opening along one side and releasing many, small, flat, brownish seeds with long, white, silky parachutes. All parts of the plants may contain small quantities of white, milky juice. Flowers from late June until autumn.
Habitat: Dog-strangling vine occurs in several localities in southern Ontario, growing in ravines, hillsides, waste areas, fence lines and hedges.
Similar Species: It is distinguished by its perennial vine habit, opposite leaves, purplish flowers, slender seedpods with parachute seeds, and somewhat milky juice.
Caution: This plant should be regarded with suspicion as it was included in early books on poisonous plants.
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