Ontario Weeds: Whorled milkweed

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Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents

  1. Name
  2. Other Names
  3. Family
  4. General Description
  5. Stems and Roots
  6. Flowers and Fruit
  7. Habitat
  8. Similar Species
  9. Caution
  10. Related Links

Name: Whorled milkweed, Asclepias verticillata L.,

Other Names: asclépiade verticillée

Family: Milkweed Family (Asclepiadaceae)

General Description: Perennial, reproducing only by seed.

Photos and Pictures

Whorled milkweed.

Whorled milkweed.

Stems & Roots: Stems erect, 20-90cm (8-36in.) high, sparingly branched in the upper part, slender, 1 or several from a cluster of fibrous roots; bases of old stems often persisting; leaves very narrow, in whorls of 3 to 6 at each node of the stem; flowers and seedpods similar to Common milkweed but the clusters are smaller and fewer-flowered.

Flowers & Fruit: Flowers smaller and greenish, and the seedpods smaller, thinner, and lacking the soft, warty bumps. Flowers from July to September.

Habitat: Whorled milkweed occurs in dry open areas in pastures, around woods, and along roadsides in the western portion of southern Ontario.

Similar Species: It is distinguished by its slender, erect stems with whorls of 3 - 6 narrow leaves, its flowers in umbels and all plant parts containing a milky juice.

Caution: It is poisonous to livestock.

Related Links

... on general Weed topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control

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