Erigeron canadensis

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Erigeron canadensis
Erigeron canadensis from Britain by D Merrick 14.jpg
Status TNC G5.svg
Secure  (NatureServe)
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Erigeron
Species:
E. canadensis
Binomial name
Erigeron canadensis
Synonyms [1]
Alphabetical list
    • Aster canadensis(L.) E.H.L.Krause
    • Caenotus canadensis(L.) Raf.
    • Caenotus pusillusRaf.
    • Conyza canadensis(L.) Cronquist
    • Conyza parvaCronquist
    • Conyzella canadensis(L.) Rupr.
    • Erigeron myriocephalusRech.f. & Edelb.
    • Erigeron paniculatusLam.
    • Erigeron pusillusNutt.
    • Erigeron ruderalisSalisb.
    • Erigeron strictusDC.
    • Inula canadensisBernh.
    • Leptilon canadense(L.) Britton
    • Leptilon pusillum(Nutt.) Britton
    • Marsea canadensis(L.) V.M.Badillo
    • Senecio ciliatusWalter
    • Tessenia canadensis(L.) Bubani
    • Trimorpha canadensis(L.) Lindm.
Canadian fleabane (Erigeron canadensis) essential oil in a clear glass vial CanadianFleabaneEssentialOil.png
Canadian fleabane (Erigeron canadensis) essential oil in a clear glass vial

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. 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.

Contents

Description

Erigeron canadensis is an annual, herbaceous plant growing to 1.5 metres (5 feet) tall, with sparsely hairy stems. The leaves are unstalked, slender, 2–10 centimetres (0.8–3.9 inches) long, and up to 1 cm (0.4 in) wide, with a coarsely toothed margin. They grow in an alternate spiral up the stem, and the lower ones wither early. The flower heads are produced in dense inflorescences and are 1 cm (0.4 in) 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. [2]

Erigeron canadensis can easily be confused with Erigeron sumatrensis , which may grow to a height of 2 m (6.6 ft), and the more hairy Erigeron bonariensis , which does not exceed 1 m (3.3 ft). E. canadensis is distinguished by bracts that have a brownish inner surface with no red dot at the tip, and are free (or nearly free) of the hairs found on the bracts of the other species. [3] [4] [5]

Distribution and habitat

Horseweed originated in North America and Central America and is widespread in its native range. [6] It has spread to inhabited areas of most of the temperate zone of Asia, [7] Europe, [2] [8] and Australia. [9] It is found in Britain from northern Scotland to Cornwall, growing as a weed of arable land and man-made environments. It is considered invasive in China. [10]

Horseweed can grow in a range of natural habitats, from sand dunes to old fields, as well as in gardens and other disturbed areas. [11] It is an indicator for disturbance because it often colonizes disturbed areas in which it was sparse or absent prior to the disturbance. [12] Horseweed is a common pest of agricultural fields, and can tolerate a range of acidic to neutral soils (pH 4.8 to 7.2). [13]

Weed status

Horseweed is commonly considered a weed, and in Ohio, Oregon, and some other locations, [14] it has been declared a noxious weed. [15] [16] It was the first weed to have developed glyphosate resistance, reported in 2001 from Delaware. [17]

It can be found in fields, meadows, and gardens throughout its native range. Horseweed infestations (specifically of 105 plants per 10 ft2) have reduced soybean yields by as much as 83%, [18] with one estimate claiming it can reduce yields by up to 90%. [19] Severe infestations have reduced sugar beet yields by 64%. [18]

It is an especially problematic weed in no-till agriculture, as it is often resistant to glyphosate [17] and other herbicides. [20] Farmers are advised to include 2,4-D or dicamba in a burndown application prior to planting to control horseweed. [21] [22]

Ecology

Horseweed produces a large amount of seeds that are dispersed by wind, allowing it to easily colonize disturbed soils. [13]

The seeds can germinate at any time of year with sufficient moisture and proper temperatures. With fall germination, it overwinters as a rosette and bolts in the spring to flower in the summer. With spring germination, it spends less time as a rosette before bolting to flower. [13] The seeds can persist in the seedbank of disturbed and non-disturbed sites, though it is more prevalent in disturbed sites. [23]

The seeds are capable of persisting in the seedbank after a fire, [24] and the plant increases in frequency in response to more frequent fire regimes. [25]

Uses

The Zuni people insert the crushed flowers of E. canadensis var. canadensis into the nostrils to cause sneezing, relieving rhinitis. [26] The Seminole people used it for cold and cough medicine, the Iroquois people used it to help combat fevers, and the Navajo and Chippewa peoples used it for stomach pain. [13] Other medicinal applications include use as a nervine, stimulant, and antiplasmodic. [27]

Standard form

Other forms

References

  1. 1 2 "Erigeron canadensis L." Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2020-08-16.
  2. 1 2 "Canadian Fleabane: Conyza canadensis". NatureGate. Retrieved 2013-12-31.
  3. ↑ Conyza sumatrensis, International Environmental Weed Foundation.
  4. ↑ Green, Deane (31 August 2011). "Horseweed, Marestail" . Retrieved 2014-08-09.
  5. ↑ Flora of North America, Conyza canadensis (Linnaeus) Cronquist, Bull. Torrey Bot. Club. 70: 632. 1943. Vergerette du Canada.
  6. ↑ Biota of North America Program, 2014 county distribution map, Erigeron canadensis.
  7. ↑ Flora of China, Erigeron canadensis Linnaeus, Sp. Pl. 2: 863. 1753. 小蓬草 xiao peng cao
  8. ↑ Altervista Flora Italiana, Cespica canadese, avoadinha, Berufkraut, Erigeron canadensis L. includes photos and European distribution map
  9. ↑ Atlas of Living Australia, Conyza canadensis (L.) Cronquist Canadian Fleabane
  10. ↑ Wu, Bingde; Zhang, Huanshi; Jiang, Kun; Zhou, Jiawei; Wang, Congyan (2019). "Erigeron canadensis affects the taxonomic and functional diversity of plant communities in two climate zones in the North of China". Ecological Research. 34 (4): 535–547. Bibcode:2019EcoR...34..535W. doi:10.1111/1440-1703.12024. S2CID   198244222.
  11. ↑ Weakley, A. S. (2015). Flora of the Southern and Mid-Atlantic States. Chapel Hill, NC, University of North Carolina Herbarium.
  12. ↑ Brewer, J. Stephen; Bertz, Christine A.; Cannon, Jeffery B.; Chesser, Jason D.; Maynard, Erynn E. (March 2012). "Do natural disturbances or the forestry practices that follow them convert forests to early‐successional communities?". Ecological Applications. 22 (2): 442–458. doi:10.1890/11-0386.1. ISSN   1051-0761. JSTOR   41416774. PMID   22611846 . Retrieved 19 July 2025.
  13. 1 2 3 4 Tilley, D. 2012. Plant Guide for Canadian horseweed (Conyza canadensis). USDA-Natural Resources Conservation Service, Aberdeen, ID Plant Materials Center. 83210-0296.
  14. ↑ "Appendix H.Noxious and Invasive WeedControlPlan" (PDF).
  15. ↑ "Erigeron canadensis". Germplasm Resources Information Network . Agricultural Research Service, United States Department of Agriculture . Retrieved 2017-12-18.
  16. ↑ "Noxious Weed Program | Deschutes County Oregon". www.deschutes.org. Retrieved 2023-06-13.
  17. 1 2 VanGessel, Mark J. (2001). "Glyphosate-resistant horseweed from Delaware". Weed Science. 49 (6): 703–705. doi:10.1614/0043-1745(2001)049[0703:RPRHFD]2.0.CO;2. JSTOR   4046416. S2CID   86256252.
  18. 1 2 "Marestail (Horseweed)". Weeds. Retrieved 2023-06-13.
  19. ↑ Froemke, A. M. (April 24, 2020). "HORSEWEED (ERIGERON CANADENSIS) CONTROL IN NO-TILL SOYBEAN SYSTEMS ON A COARSE TEXTURED SOIL" (PDF). North Dakota State University. Retrieved June 13, 2023.
  20. ↑ Kruger, Greg R.; Davis, Vince M.; Weller, Stephen C.; Johnson, William G. (2010). "Growth and Seed Production of Horseweed (Conyza canadensis) Populations after Exposure to Postemergence 2,4-D". Weed Science. 58 (4): 413–419. doi:10.1614/WS-D-10-00022.1. S2CID   55366555.
  21. ↑ Dilliott, Meghan; Soltani, Nader; Hooker, David C.; Robinson, Darren E.; Sikkema, Peter H. (March 15, 2022). "When using glyphosate plus dicamba, 2,4-D, halauxifen or pyraflufen/2,4-D for glyphosate-resistant horseweed (Erigeron canadensis) control in soybean, which third mix partner is better, saflufenacil or metribuzin?". Weed Technology. 36 (2): 295–302. doi: 10.1017/wet.2022.18 . ISSN   0890-037X.
  22. ↑ "Horseweed/Marestail". Take Action. Retrieved 2023-06-13.
  23. ↑ Cohen, Susan; Braham, Richard; Sanchez, Felipe (December 2004). "Seed Bank Viability in Disturbed Longleaf Pine Sites". Restoration Ecology. 12 (4): 503–515. doi:10.1111/j.1061-2971.2004.00382.x.
  24. ↑ Creech, M. N., et al. (2012). "Alteration and Recovery of Slash Pile Burn Sites in the Restoration of a Fire-Maintained Ecosystem." Restoration Ecology 20(4): 505-516.
  25. ↑ Burton, J. A. (2009). Fire frequency effects on vegetation of an upland old growth forest in eastern Oklahoma. Environmental Science. Stillwater, Oklahoma, Oklahoma State University. Bachelor: 78.
  26. ↑ Stevenson, Matilda Coxe 1915 Ethnobotany of the Zuni Indians. SI-BAE Annual Report #30 (p.55).
  27. ↑ Rafinesque, C. S. (1828). Medical flora; or Manual of the medical botany of the United States of North America.

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