Horseweed, Marestail, Horsetail, Canadian Horseweed, Canadian Fleabane, Fleabane, Hogweed, Coltstail, Butterweed
Erigeron canadensis L.
Syn. Conyza canadensis (L.) Cronquist
Synonyms of Erigeron canadensis (31)(Updated 10-19-21 from Plants of the World Online): Aster canadensis (L.) E.H.L.Krause, Caenotus canadensis (L.) Raf., Caenotus pusillus Raf., Conyza canadensis (L.) Cronquist, Conyza canadensis var. glabrata (A.Gray) Cronquist, Conyza canadensis var. incisa P.D.Sell, Conyza canadensis var. obovoidea P.D.Sell, Conyza canadensis var. pusilla (Nutt.) Cronquist, Conyza canadensis var. robusta P.D.Sell, Conyza canadensis var. simplex P.D.Sell, Conyza parva Cronquist, Conyzella canadensis (L.) Rupr., Erigeron canadensis f. coloratus Fassett, Erigeron canadensis var. glabratus A.Gray, Erigeron canadensis var. grandiflorus Schwein., Erigeron canadensis var. pusillus (Nutt.) B.Boivin, Erigeron canadensis var. strictus Farw., Erigeron myriocephalus Rech.f. & Edelb., Erigeron paniculatus Lam., Erigeron pusillus Nutt., Erigeron ruderalis Salisb., Erigeron setiferus Post ex Boiss., Erigeron strictus DC., Inula canadensis Bernh., Leptilon canadense (L.) Britton, Leptilon canadense var. pusillum (Nutt.) Daniels, Leptilon pusillum (Nutt.) Britton, Marsea canadensis (L.) V.M.Badillo, Senecio ciliatus Walter, Tessenia canadensis (L.) Bubani, Trimorpha canadensis (L.) Lindm.
Erigeron canadensis L. is the correct and accepted scientific name for this plant. The genus and species were named and described as such by Carl von Linnaeus in the second volume of the first edition of Species Plantarum in 1753. Many websites are still using the name Conyza canadensis (L.) Cronquist which was named and described as such by Arthur John Cronquist in the Bulletin of the Torrey Club in 1943.
Plants of the World Online lists 455 species in the Erigeron genus (as of 10-20-21 when this page was last updated). It is a member of the plant family Asteraceae with 1,677 genera. Those numbers could change as updates are made on POWO. The number of genera in the family fluctuates quite often.
As you can see by the map above provided by Plants of the World Online, Erigeron canadensis is a very widespread species. Areas in green are where it is native and purple is where it has been introduced. The map on the USDA Plants Database for North America is about the same but includes another province in Canada.
The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations.
THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH BETTER POSITIVE ID.
Hardly anyone in rural areas or even in the city has not come across the Horsetail. They grow just about anywhere, even in cracks in sidewalks, alleys, along backroads, old foundations, fence rows… You get the picture. The species has many common names including Horseweed, Marestail, Horsetail, Canadian Horseweed, Canadian Fleabane, Fleabane, Hogweed, Coltstail, Butterweed, and maybe others.
Erigeron canadensis is an annual weed with a strong ascending growth habit. They generally start branching out toward the upper part of the stem and produce LOADS of flowers and seeds. The long, lance-shaped leaves are arranged in an alternate pattern along the stems. The stems and leaf margins are covered with white hairs.
The multitude of flowers produce seeds that are carried through the wind.
I am not going to go into great detail with technical language because this plant is very easy to identify. If you want a complete description you can check some of the links below.
I find it very interesting this plant is edible, so be sure to check out the link below to EDIBLE WILD FOOD.
Remember if you are doing research about this plant it can be listed as either Conyza canadensis OR Erigeron canadensis. Who knows which name will eventually win the prize…
I have enjoyed photographing and learning about the many wildflowers growing on the farm and other areas. I have grown over 500 different plants and most have pages listed on the right side of the blog. I am not an expert, botanist, or horticulturalist. I just like growing, photographing, and writing about my experience. I rely on several websites for ID and a horticulturalist I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.
I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at firstname.lastname@example.org. I would enjoy hearing from you.
Note: Some websites are not up-to-date with the scientific name changes and the numbers may not be the same. Plants of the World Online by Kew makes regular updates.
FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
ARTICLE BY MELODY ROSE ON DAVE’S GARDEN
MSU-MIDWEST WEEDS AND WILDFLOWERS
USDA PLANTS DATABASE
LADY BIRD JOHNSON WILDFLOWER CENTER
KANSAS WILDFLOWERS AND GRASSES
PFAF (PLANTS FOR A FUTURE)
EDIBLE WILD FOOD
NORTH CAROLINA STATE UNIVERSITY
THE JEPSON HERBARIUM
NOTE: The figures may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is the most reliable and up-to-date plant database and they make updates on a regular basis. I make updates at least once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂