Horseweed - Erigeron Canadensis

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  • Horseweed - Erigeron Canadensis
  • Horseweed - Erigeron Canadensis
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Horseweed gets its common name from terpene, a substance produced by the plant that irritates any mammals that touch it  

Farmers noticed that horses who had come in contact with Erigeron Canadensis developed minor rashes on the tips of their noses.Some people are also susceptible to developing irritation or a rash when exposed to Erigeron Canadensis’ here.While Horseweed is generally disliked today, it was considered helpful by aboriginal people in the Americas. Erigeron Canadensis Erigeron Canadensis was commonly used to treat bleeding problems, flesh wounds, ulcers, hemorrhoids, high blood pressure, tonsillitis, and help kidneys flush excess salt and fluids. Indigenous people and early colonials also used it to treat many heart conditions. Other names for Erigeron Canadensis include Canadian Horseweed and Mare’s Tail.


Horseweed Appearance

Horseweed is a flowering, summer annual that can from anywhere from six inches to ten feet tall.

The central stem is solid and stout and covered in spreading white hairs. It is unbranched until the apex, at which point there are branched stems that produce flowers.When immature, Erigeron Canadensis has strong similarities to Goldenrod; however, the differences are easy to spot when Erigeron Canadensis produces flowers and seeds out. Horseweed has white flowers.

The flowers have very yellow centers with forty to 50 white petals on each flower. Even at their full size, these flowers are only one-eighth of an inch across, so they are not easy to spot from afar. The leaves are oval-shaped, narrow, and covered in tiny, white, stiff hairs.The leaves are about a half-inch wide and four inches long at the plant’s largest size at full maturity.


Where Horseweed Grows

Erigeron Canadensis prefers full sun, loamy soil, and dry heat. Horseweed can tolerate gravel and clay soil, though it is not favored. Horseweed also prefers fertile soil; the more nutrients the earth has, the taller and more comprehensive it will grow. It can tolerate droughts quite well, though it may drop some lower leaves in the process. Erigeron Canadensis is native to Central and South America; however, it is considered invasive in Europe, Asia, and Australia. In the United States, it grows in every state, Hawaii and Alaska included. Horseweed is a prolific producer that produces by seeds alone. It creates approximately 700,000 seeds per pound, and the seeds are pretty hardy, clinging to animals and clothing for long distances before falling off and germinating. Usually, the plant can be found in vacant lots, gravel parking lots, ditches, canals, roadsides, along railroad tracks, in meadows, agricultural crop fields, orchards, vineyards, and other unmanaged places.


Erigeron Canadensis Attracts Pollinators and Other Insects

The flowerheads attract a vast array of insects, including:

  • Wasps
  • Flies
  • Honeybees
  • Halictid bees
  • Flower beetles

Horseweed is full of resin and poisonous, so most mammals leave it alone. Occasionally, deer and rabbits will selectively forage on young and immature Horseweed.

The flowers bloom from June through September, when you will commonly see these insects near them.

Horseweed, commonly known as mare's tail, is a broadleaf summer annual or biennial plant. It can be found on agricultural land, disturbed managed sites, and landscaped areas up to 6600 feet (2000 meters) in elevation across California. It grows in disturbed regions where natural vegetation has been disturbed. You can find it on the hillsides of coastal sage scrub during wet years. It is a fierce competitor for water and has a quick growth rate.

Horseweed is a summer-growing annual or bi-annual plant found throughout California. Its original country is Canada, but you may also find it in Europe, Russia, Siberia, Asia, and other parts of the world. It thrives in all types of damp soil. It is typically found on the hillsides of coastal locations and requires water to thrive. It grows swiftly near water and quickly takes over agricultural lands, landscaped properties, and other locations where vegetation has been chopped down or uprooted. Horseweed's primary habitats include canals, ditches, crop fields, vineyards and orchards, and other uncontrolled properties.

The immature plant produces a low, developing rosette of hairy leaves. Horseweed grows as a winter annual and produces the rosette in late summer. When the plant matures, it produces a single, hairy stem that can grow around five feet tall. From mid-to late-summer, tiny white blooms with yellow centers bloom, resembling small daisies. They are found on lateral branches towards the plant's highest growth.

It is a plant that produces a lot of seeds. A single plant can yield over 200,000 seeds, which can be carried up to a quarter-mile by the wind. Horseweed is especially common in poorly maintained landscapes, nurseries, and agricultural environments. It can develop on turfgrass, although it isn't a problem in well-kept (frequently mowed) turf. Horseweed should not be confused with horsetail, a distinct plant that requires different herbicides.Horseweed has a shallow taproot and a fibrous root structure. It may be possible to remove tiny plants depending on the soil conditions. This weed can also be efficiently reduced by mulching in ornamental plant areas. Pre-emergent herbicides include dichlobenil (Casoran), dithiopyr (Dimension), flumioxazin (SureGuard), oxadiazon (Ronstar), oxyfluorfen (Goal), and oxyfluorfen+prodiamine (Biathlon). All this is classified as the nursery and grounds care rather than lawn and landscape.

Horseweed's therapeutic characteristics have long been used to treat diarrhea and keep parasites from livestock. Fleabane is another name for it, and it originates from the fact that it contains thymol, a flea killer.

Horseweed may be found in almost every field, and it can be seen in enormous numbers in the spring. Many herbicides used for burndown in conservation tillage farming systems are resistant or tolerable. Tennessee's conservation tillage acres have effectively diminished as a result of this. According to a recent survey, conservation tillage farming systems produce Horseweed in the rosette stage.

Horseweed is a popular food source for tarnished plant bugs, a severe cotton pest. Horseweed includes volatile oils, tannic acid, and gallic acid, which can irritate mucous membranes and skin in livestock and people. Horses are particularly vulnerable. Horseweed was used as an astringent by Native Americans in the Plains States, and it was also utilized to treat diarrhea and dysentery by early settlers.

Zone: 6-9

Flower Color: White, Yellow

Size at maturity: 5 feet tall

Soil Type: Moisture

Bloom Time: Summer

Bloom Color: White, Yellow

Shipped as: Bareroot


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