Horseweed

Kendall County (IL) Forest Preserve District

Horseweed
Conyza canadensis (Erigeron canadensis) [C-value 1]
Aster family (Asteraceae)
Blooms mid-July - October

The native Horseweed is very common in our area. It prefers full sun and slightly moist to dry conditions. Habitats include disturbed areas of upland prairies and weedy meadows, abandoned fields, pastures, gravelly lots, and miscellaneous waste areas. It is a summer annual that ranges in size from ½' to 7' tall and is unbranched, except for the flowering stems toward its apex. The stout central stem, covered with white hairs, has alternate leaves 2–3½" and ¼–½" across and lance-shaped. The central stem terminates in a panicle of flowerheads up to 1½' long and ½' across. The individual white flowers are only about 1/8" across that later develop achenes with tufts of white hair.

Horseweed at Rose Hill Subdivision August 22, 2013

Horseweed along Fox River September 17, 2014

Horseweed foliage along Fox River September 17, 2014

Horseweed at Rose Hill Subdivision September 15, 2012 (after blooming)

Horseweed at Jay Woods Forest Preserve November 3, 2014 (with mature seeds)

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