Figure 68.—Horseweed (Erigeron canadensis)

Synonym

Leptilon canadense (L.) Britton.

Other Common Names

Erigeron, mare's-tail, Canada erigeron, butterweed, bitterweed, cow's-tail, colt's-tail, fireweed, bloodstanch, hogweed, prideweed, scabious.

Habitat And Range

Horseweed is common in fields and waste places and along roadsides throughout almost all of North America.

Description

This weed varies greatly in height according to the soil it grows in. The erect stem, sometimes smooth, but usually bristly hairy, is generally branched near the top. The leaves are usually somewhat hairy, the lower ones 1 to 4 inches long and toothed, those scattered along the stem are rather narrow and smooth. From June to November the plant produces numerous heads of small, inconspicuous white flowers, followed by an abundance of seed.

Part Used

The entire herb, collected during the flowering period. Oil of erigeron, obtained from the plant by distillation, is produced commercially in Michigan and Indiana.

Information on the extraction of volatile oils from plants is contained in the following publication:Sievers, A.F. Methods of extracting volatile oils from plant material and the production of such oils in the United States. U.S. Dept. Agr. Tech. Bul. 16, 36 p. illus. 1928