Ontario Weeds: Canada fleabane

Table of Contents

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

Name: Canada fleabane, Erigeron canadensis L.,

Other Names: Bitterweed, Fleabane, Hogweed, Horseweed, Mare's-tail, vergerette du Canada, vergerolle du Canada, érigéron du Canada, queue de renard, Conyza canadensis (L.) Cronq.

Family: Composite or Aster Family (Compositae) 

General Description: Annual or winter annual, reproducing only by seed.

Photos and Pictures

Canada fleabane. A. Base of plant. B. Top of flowering stem.

Stems & Leaves: Stems, erect, 10-180cm (4in.-5ft) high, hairy, little branched; leaves alternate (1 per node) but numerous and often appearing opposite (2 per node), soft-hairy at first but becoming harsh on older leaves, bright green; basal and lower stem leaves narrowly oval, rarely more than 1cm (2/5in.) wide, tapering to a slender stalk, with a few, scattered, shallow teeth or without teeth; middle and upper leaves linear, very narrow and usually without teeth.

Flowers & Fruit: Flower heads 3-5mm (1/8-1/5in.) across, very numerous on many short branches near the top of the main stem; ray florets white but very short and usually concealed by the slightly longer involucral bracts around each flower head; disk florets yellowish; very fluffy at maturity. The leaves and other parts of the plant when crushed have a faint but distinctive odour reminiscent of carrots. Flowers from July to late autumn.

Habitat: Canada fleabane occurs throughout Ontario in grainfields, pastures, waste places, roadsides and gardens.

Similar Species: It is distinguished by its numerous, narrow, mostly toothless bright green leaves gradually decreasing in size from base to top of plant, its numerous, small, yellow-green flower heads lacking conspicuous ray florets, its odour suggestive of carrots, and its fluffy appearance when mature.

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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