Ontario Weeds: Swamp milkweed
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
Swamp milkweed. B. Flowering stem with 10 simple umbels.
Swamp milkweed. A. Base of plant. C. Two seedpods from 2 flowers of 1 umbel.
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
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.
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