Canada Fleabane, Canadian horseweed

Conyza canadensis

Physical Characteristics

Conyza canadensis is a ANNUAL growing to 1 m (3ft 3in) by 0.5 m (1ft 8in). See above for USDA hardiness. It is hardy to UK zone 7. It is in flower from June to October, and the seeds ripen from July to October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Bees, flies. It is noted for attracting wildlife. Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil and can tolerate drought.

Distribution

N. America. Naturalized in Britain[17].

Habitats

Cultivated Beds; East Wall. By. South Wall. By. West Wall. By.

Edible Uses

Edible Parts: Leaves Edible Uses: Condiment Young leaves and seedlings - cooked[105, 177]. Boiled, cooked in rice or dried for later use[183]. A nutritional analysis of the leaves is available[218]. The source of an essential oil that is used commercially for flavouring sweets, condiments and soft drinks[183]. The fresh leaves contain 0.2 - 0.66% essential oil[218].

Medicinal Uses

Astringent Diuretic Dysentery Emmenagogue Homeopathy Hypoglycaemic Styptic Tonic VD Vermifuge In traditional North American herbal medicine, Canada fleabane was boiled to make steam for sweat lodges, taken as a snuff to stimulate sneezing during the course of a cold and burned to create a smoke that warded off insects[254]. Nowadays it is valued most for its astringency, being used in the treatment of gastro-intestinal problems such as diarrhoea and dysentery[254]. It is said to be a very effective treatment for bleeding haemorrhoids[254]. The whole plant is antirheumatic, astringent, balsamic, diuretic, emmenagogue, styptic, tonic and vermifuge[4, 7, 9, 21, 222]. It can be harvested at any time that it is in flower and is best used when fresh[4, 207, 238]. The dried herb should not be stored for more than a year[238]. The seeds can also be used[4]. An infusion of the plant has been used to treat diarrhoea and internal haemorrhages[213] or applied externally to treat gonorrhoea[213] and bleeding piles[7]. The leaves are experimentally hypoglycaemic[218]. The essential oil found in the leaves is used in the treatment of diarrhoea, dysentery and internal haemorrhages[4, 207, 218]. It is a uterine stimulant[213] and is also said to be valuable in the treatment of inflamed tonsils plus ulceration and inflammation of the throat[4]. A tea of the boiled roots is used to treat menstrual irregularities[213]. A homeopathic remedy is made from the plant[9]. It is used in the treatment of haemorrhoids and painful menstruation[9].

Known Hazards

Skin contact with the plant can cause dermatitis in some people[222].