Canada Fleabane, Canadian horseweed
Conyza canadensis

Family: Asteraceae or Compositae

What it is like

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.

Height (m): 1

Where it is found

Light soils on waste and cultivated land, also on walls, avoiding acid soils in Britain.

N. America. Naturalized in Britain.

Conservation Status: This taxon has not yet been assessed.

Countries/locations it is found in

Native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia.

How it is used

Food

Rating: 1

Young leaves and seedlings - cooked. Boiled, cooked in rice or dried for later use. A nutritional analysis of the leaves is available. The source of an essential oil that is used commercially for flavouring sweets, condiments and soft drinks. The fresh leaves contain 0.2 - 0.66% essential oil.

Condiment: the various plants that are used as flavourings, either as herbs, spices or condiments.

Medicine

Rating: 3

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. Nowadays it is valued most for its astringency, being used in the treatment of gastro-intestinal problems such as diarrhoea and dysentery. It is said to be a very effective treatment for bleeding haemorrhoids. The whole plant is antirheumatic, astringent, balsamic, diuretic, emmenagogue, styptic, tonic and vermifuge. It can be harvested at any time that it is in flower and is best used when fresh. The dried herb should not be stored for more than a year. The seeds can also be used. An infusion of the plant has been used to treat diarrhoea and internal haemorrhages or applied externally to treat gonorrhoea and bleeding piles. The leaves are experimentally hypoglycaemic. The essential oil found in the leaves is used in the treatment of diarrhoea, dysentery and internal haemorrhages. It is a uterine stimulant and is also said to be valuable in the treatment of inflamed tonsils plus ulceration and inflammation of the throat. A tea of the boiled roots is used to treat menstrual irregularities. A homeopathic remedy is made from the plant. It is used in the treatment of haemorrhoids and painful menstruation.

Astringent: Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.

Diuretic: Acts on the kidneys, promoting the flow of urine.

Dysentery: Used in treating dysentery - an infection of the intestines that causes diarrhoea containing blood or mucus.

Emmenagogue: Promotes or increases the menstrual flow. In early stages of pregnancy it can induce an abortion.

Homeopathy: A plant used in homeopathic treatments.

Hypoglycaemic: Reduces the levels of sugar in the blood.

Styptic: An astringent that stops bleeding by contracting the blood vessels.

Tonic: Improves general health. Slower acting than a stimulant, it brings steady improvement.

VD: Used in the treatment of venereal disease

Vermifuge: Expels and kills internal parasites.

Other

Rating: 1

The plant contains small quantities of essential oil. Since the plant is readily obtainable, extraction of the oil is feasible - it has a special quality that would make it suitable in the making of perfumes with unusual nuances.

Essential: Essential oils that are used in perfumery, medicines, paint solvents, insect repellents etc.

Attracts Wildlife: Plants noted for attracting wildlife

Scented Plants: Plants noted for their scent

How it is grown

Prefers a well-drained light or medium neutral to alkaline soil in a sunny position, though it tolerates most conditions. Originally from N. America, Canada fleabane has become naturalized in many areas of the world and is considered to be a nuisance weed in many areas. The plant is very adaptable to differing conditions and can vary dramatically in height, from only a few centimetres in poor soils to as much as 3 metres tall in rich soils. The plant is used commercially as a food flavouring. A good bee plant but unfortunately it also harbours various insect pests such as the tarnished plant bug.

Propagating it: Seed - we have no information on this species but suggest sowing the seed in spring in situ. An autumn sowing in situ might also be worthwhile.

Best place to grow: Cultivated Beds; East Wall. By. South Wall. By. West Wall. By.

Habit: Annual

Hardiness: 6-9

Growth:

Soil: Light (sandy), medium

Shade: Semi-shade, no shade

Moisture: Dry, moist

Things to keep in mind

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

A common weed in temperate to tropical regions.

Its other names

Local names

Canadian fleabane. horseweed. Spanish: erigeron del Canada; escoba dura; hierba de caballo; hierba impia; olivarda. French: erigéron du Canada; vergerette du Canada. Portuguese: avoadinha. Canada: mare's tail. Colombia: cvenadillo. Cuba: conyza; zancarana. France: erigeron de Canada; vergerette de Canada. Germany: Kanadischer berufkraut; Kanadisher katzenschweif. India: jarayupriya. Iraq: thail el-faras. Italy: impi; saeppola. Japan: himemukashiyomogi. Madagascar: sarijamala. Mauritius: herbe gandi. Mexico: pegajosa. Netherlands: fijnstraal, Canadeese. Norway: canadese fijnstraal; hestehamp. Poland: przymiotno kasnadyjskie. Puerto Rico: pascueta; rozuz. South Africa: armoedskruid; kanadese skraalhans. Spain: altabaca; canem bord; erigeron de Canada; zamarraga. Sweden: kanadabinka. Turkey: sifa out. USA: butterweed; Canada horseweed; fireweed; hogweed. Yugoslavia (Serbia and Montenegro): repusnjaca.

Synonyms

Erigeron canadensis.