Ministry of Agriculture, Food and Rural Affairs

Ontario Weeds: Swamp milkweed

Table of Contents

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

Name: Swamp milkweed Asclepias incarnata L.,

Other Names: asclépiade incarnate

Family: Milkweed Family (Asclepiadaceae)

General Description: Perennial, reproducing by seed and possibly by rhizomes.

Photos and Pictures

Stems & Roots: Stems erect, stout, 30-150cm (12-60in.) high, with little milky juice and few, if any, hairs; leaves opposite, rather numerous, lanceolate to elliptic, 4.5-20cm (1¾-8in.) long with fine veins clearly visible on the underside.

Flowers & Fruit: Inflorescence broad, usually formed from several umbels of flowers; flowers pink to rose-purple (rarely whitish), similar to those of Common milkweed but more slender; fruits slender pods with elongated tips, rusty-green, splitting lengthwise at maturity; seeds brown, flat, with winged margins and tufts of long, silky, white hair. Flowers from June to August.

Habitat: Swamp milkweed is found in swamps, ditches and other wet areas in woods, fields and roadsides in southern and central Ontario.

Similar Species: It is distinguished from other milkweeds by its numerous, slender leaves, its pink to rose-purple flowers and its slender, non-warty pods, and from other narrow-leaved plants by its smooth stems, slender, opposite leaves and somewhat milky juice.

Caution: It is considered 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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