Conyza sumatrensis

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Conyza sumatrensis

Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Asterales
Family: Asteraceae
Tribe: Astereae
Genus: Conyza
Species: C. sumatrensis
Binomial name
Conyza sumatrensis

Of the alien British Conyza species, Conyza sumatrensis is the second most abundant (after C. canadensis) and is common on waste ground, railways and disturbed ground in London and south east England. It is known by the floral bracts which are distinctly hairy (in contrast to C. canadensis and C. bilbaoana) and by the leaf margin hairs (which are bent forward rather than spreading at right angles as in C. canadensis). It flowers in August and September and has dirty white or rust coloured pappus hairs. Although an abundant alien, it is not invasive in any natural or semi-natural habitats.


It is common on waste ground, railways and disturbed ground. It is known by the floral bracts which are distinctly hairy (in contrast to C. canadensis and C. bilbaoana) and by the leaf margin hairs (which are bent forward rather than spreading at right angles as in C. canadensis). It flowers in August and September and has dirty white or rust coloured pappus hairs. Although an abundant alien, it is not invasive in any natural or semi-natural habitats.

Originating in the American continent, this is an introduced weed in the UK, which in certain countries has started to exhibit resistance to herbicides.[1]

In Britain, of the alien British Conyza species, this is the second most abundant (after C. canadensis) and is typically found in London and the South East of England.

It is also found in countries such as: Japan, Malaysia, Taiwan, Sri Lanka, Australia.

[edit] Plant Details

Type Details Comments
Scientific Name Conyza sumatrensis Synonyms: Conyza albida, Conyza altissima, Conyza nandina
Common Names fleabane, tall fleabane, broad-leaved fleabane, white horseweed, Sumatran fleabane, Guernsey fleabane
Family Asteraceae
Seasonality Annual
Height 1-2 metres when fully grown (summer/autumn)
Description Looking somewhat like the more common Rosebay Willowherb, its flowers are white rather than purple-pink. Its leaves are like dandelion leaves, but longer, thinner and more like primrose leaves in colour and texture. Its seeding heads are like dandelions, but straw couloured and smaller. The white flowers are like cornflowers, but smaller, and clustered like cow-parsley. (Excellent pictures.[2])
Toxicity (References needed)
Threat to other plants It poses a significant threat to wildlife conservation areas and other reserves. Its invasive nature and competitive ability could suppress the native flora in the more open habitats it favours.
Origin South America
Spread North America
UK First recorded in London[3] (by Brian Wurzell) in 1984
France St Sozy[4] (Dordogne) 2006
Netherlands[5]
Japan[6]
Malaysia, Taiwan, Sri Lanka, Australia

[edit] References

  1. ^ resistance to herbicides
  2. ^ see
  3. ^ London
  4. ^ St Sozy
  5. ^ Holland
  6. ^ Japan

[edit] External links

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