Conyza canadensis

Tracheophyta MagnoliopsidaAsteraceaeConyzaConyza canadensis


An erect annual of well-drained, open habitats such as pavements, waste places, walls, railway ballast and as a weed of cultivated ground. It is particularly characteristic of urban areas of S. and E. England. It also occurs occasionally on sand dunes and on sandy ground inland. Lowland.



World Distribution

Native of N. America; naturalised throughout Europe and in similar climatic regions almost worldwide.

Broad Habitats

Light (Ellenberg): 7

Moisture (Ellenberg): 4

Reaction (Ellenberg): 7

Nitrogen (Ellenberg): 6


Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 3.8

July Mean Temperature (Celsius): 16

Annual Precipitation (mm): 766

Life form information

Height (cm): 100

Perennation - primary


Life Form - primary

Therophyte (annual land plant)



Clonality - primary

Little or no vegetative spread

Distribution information

Count of 10km squares in Great Britain: 1048

Count of 10km squares in Ireland: 11

Count of 10km squares in the Channel Isles: 10

Atlas Change Index: 1.12

Weighted Changed Factor: 63

Weighted Change Factor Confidence (90%)


Distribution information

JNCC Designations


PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.

Atlas text references