Ontario Weeds: Spotted Joe-pye Weed

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. Related Links

Name: Spotted Joe-Pye weed, Eupatorium maculatum L.,

Other Names: eupatoire maculée, eupatoire pourpre, Eupatorium purpureum L. var. maculatum (L.) Darl

Family: Composite or Aster Family (Compositae) 

General Description: Perennial commonly found in moist or wet areas throughout most of Ontario, and reproduces from rhizomes as well as by seed.

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Photos and Pictures

Spotted Joe-Pye weed (A - plant beginning to flower; B - flower heads and seed heads).

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Stems & Roots: Grows 0.6-2.0m (2-6½ft) tall, with speckled or wholely purplish stems, these smooth or somewhat hairy; leaves mostly in whorls of 4 to 6, but may be only opposite or alternate near the inflorescence, narrowly to broadly ovate, narrowing gradually into long, stretched-out (acuminate) tips as well as towards the petiole, 10-25cm (4-10in.) long, 1-6cm (2/5-2 1/5in.) wide, on petioles 1-25mm (1/25-1in.) long; leaf margins toothed, the teeth ranging from coarsely and sharply forward-pointed (serrate) to shallow and somewhat rounded.

Flowers & Fruit: Flowers in pink to light purple flower heads, each head 2-5 mm (1/12-1/5in.) in diameter and 5-10mm (1/5-2/5in.) long, with 10-20 tubular florets and no ray florets; the many heads clustered into a compact, broad, rounded to flat-topped, compound inflorescence. Flowers in August and September.

Habitat: Spotted Joe-Pye weed is a native plant that grows in wet meadows, edges of lakes and streams, roadside ditches, and other wet places throughout Ontario.

Similar Species: It is distinguished by its broad, tapering leaves in whorls of 4 to 6 on speckled or solid purplish stems, and its pink to purplish flower heads in relatively compact clusters, and by usually growing in wet places.

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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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