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.
Photo: @roberta15631 · iNaturalist · CC BY-NC
Horseweed
Erigeron canadensis
- Observations in the area
- 2
- Last sighting
- 24 September 2025
- Category
- Plants
Species and sighting data come from the iNaturalist platform and may change over time.
Where it has been observed
More photos
Photo: @dinobiancolini · iNaturalist · CC BY-NC
Photo: @winterling · iNaturalist · CC BY-NC
Photo: Zihao Wang · iNaturalist · CC BY
Photo: Scott Morris · iNaturalist · CC BY
Photo: El Picaro Azul · iNaturalist · CC BY-NC
Photo: @AnRo0002 · iNaturalist · Pubblico dominio
Photo: Gilles San Martin · iNaturalist · CC BY-SA
Photo: Michael J. Papay · iNaturalist · CC BY
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Photo: @Gregorio.gc · iNaturalist · CC BY-SA
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Photo: @anonymous · iNaturalist · CC BY-SA
Nature data: iNaturalist
Sighting data also come from open nature platforms and may change over time.