Herbs & Plants

Conyza canadensis

Botanical Name: Erigeron Canadense
Family: Asteraceae
Tribe: Astereae
Genus: Conyza
Species: C. canadensis
Kingdom: Plantae
Order: Asterales

Synonyms: Fleawort. Coltstail. Prideweed.
Common names:Conyza canadensis, Horseweed, Canadian horseweed, Canadian fleabane, Coltstail, Marestail and Butterweed
Habitat: Erigeron Canadense is native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia.

Conyza canadensis is an annual plant growing to 1.5 m (60 inches) tall, with sparsely hairy stems. The leaves are unstalked, slender, 2–10 cm 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.


It has an unbranched stem, with lance-shaped leaves, the lower ones with short stalks and with five teeth, the upper ones with uncut edges and narrower, 1 to 2 inches long. The stem is bristly and grows several feet high, bearing composite heads of flowers, small, white and very numerous, blossoming from June to September.

Conyza canadensis can easily be confused with Canyza sumatrensis, which may grow to a height of 2 m, and the more hairy Canyza bonariensis which does not exceed 1 m (40 inches). Conyza 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.

Part Used in medicines:  Herb, seeds. ……. The whole herb is gathered when in bloom and dried in bunches. The seeds are also used.

Constituents: The herb contains a bitter extractive, tannic and gallic acids and a volatile oil, to which its virtues are due

Medicinal Uses: Astringent, diuretic, tonic. It is considered useful in gravel, diabetes, dropsy and many kidney diseases, and is employed in diarrhoea and dysentery.

Oil of Erigeron resembles in its action Oil of Turpentine, but is less irritating. It has been used to arrest haemorrhage from the lungs or alimentary tract, but this property is not assigned to it in modern medicine.

It is said to be a valuable remedy for inflamed tonsils and ulceration and inflammation of the throat generally.

The Zuni people insert the crushed flowers of the canadensis variety into the nostrils to cause sneezing, relieving rhinitis. It is valued by Native Americans for assisting in the clotting of the blood and it has also been used to treat rheumatic complaints and gout. A tincture is 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

The drug has a feeble odour and an astringent, aromatic and bitter taste. It is given in infusion (dose, wineglassful to a teacupful), oil (dose, 2 to 5 drops) on sugar. Fluid extract, 1/2 to 1 drachm.

The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplements, it is always advisable to consult with your own health care provider.

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