Erigeron canadensis
| Erigeron canadensis | |
|---|---|
 | |
| In the Netherlands in 2004 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Erigeron |
| Species: | E. canadensis |
| Binomial name | |
| Erigeron canadensis L.[1] | |
| Synonyms[1] | |
| |
Erigeron canadensis (synonym Conyza canadensis) is an annual plant native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia.[2] Common names include horseweed, Canadian horseweed, Canadian fleabane, coltstail, marestail, and butterweed. It was the first weed to have developed glyphosate resistance, reported in 2001 from Delaware.[3]
Description
Erigeron canadensis is an annual plant growing to 1.5 m (60 in) tall, with sparsely hairy stems. The leaves are unstalked, slender, 2–10 centimetres (0.79–3.94 in) long, and up to 1 cm (0.4 inches) across, with a coarsely toothed margin. They grow in an alternate spiral up the stem and the lower ones wither early. The flowers are produced in dense inflorescences 1 cm in diameter. Each individual flower has a ring of white or pale purple ray florets and a centre of yellow disc florets. The fruit is a cypsela tipped with dirty white down.[4]
E. canadensis can easily be confused with Erigeron sumatrensis, which may grow to a height of 2 m, and the more hairy Erigeron bonariensis, which does not exceed 1 m (40 in). E. canadensis is distinguished by bracts that have a brownish inner surface and no red dot at the tip, and are free (or nearly free) of the hairs found on the bracts of the other species.[5][6][7]
Distribution and habitat
Horseweed originated in North America and is very widespread there,[2] but has spread to inhabited areas of most of the temperate zone of Asia,[8] Europe,[4][9] and Australia.[10] It is found in Britain from northern Scotland to Cornwall, growing as a weed of arable land and man-made environments. It considered invasive in China.[11]
Weed status
Horseweed is commonly considered a weed, and in Ohio, it has been declared a noxious weed.[12] It can be found in fields, meadows, and gardens throughout its native range. Horseweed infestations have reduced soybean yields by as much as 83%.[citation needed] It is an especially problematic weed in no-till agriculture, as it is often resistant to glyphosate[3] and other herbicides.[13] Farmers are advised to include 2,4-D or dicamba in a burndown application prior to planting to control horseweed.[citation needed]
Uses
The Zuni people insert the crushed flowers of E. canadensis var. canadensis into the nostrils to cause sneezing, relieving rhinitis.[14] Other Native Americans used a preparation of the plant's leaves to treat sore throat and dysentery.[15] A tincture can be made from the dried flowering tops of the plants.
Horseweed is a preferable material for use in the hand drill-method of making friction fire.
| This article uses material from the Wikipedia article Metasyntactic variable, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License. |