Conyza canadensis (L.) Cronquist
horseweed (Canadian fleabane; Canadian horseweed)
Asteraceae (Aster family)
Introduction to Vascular Plants
horseweed (Canadian fleabane; Canadian horseweed)
Asteraceae (Aster family)
Introduction to Vascular Plants
Species Information
General:
Annual herb from a taproot; stems erect, usually single, more or less glabrous, 0.2-1.0 m tall.
Leaves:
Basal leaves lacking; stem leaves linear to linear-lanceolate or the lowermost oblanceolate, stalked, 2-10 cm long, 2-8 mm wide, glabrous.
Flowers:
Heads with ray and disk flowers, numerous in an open, leafy, branched, usually cylindric inflorescence; involucres 3-4 mm tall; involucral bracts graduated, glabrous to sparsely stiff-hairy, with a conspicuous central glandular area and narrow, more or less papery margins; ray flowers white, numerous, inconspicuous, barely exceeding the pappus; disk flowers few.
Fruits:
Achenes stiff-hairy; pappus of dirty-whitish, slender hairs.
Illustration
If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.
Illustration Source: The Illustrated Flora of British Columbia
USDA Species Characteristics
Flower Colour:
White
Blooming Period:
Indeterminate
Fruit/Seed characteristics:
Colour: Brown
Present over the
Source: The USDA
Ecology
Ecological Framework for Conyza canadensis
The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)
The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)
| Site Information |
Value / Class |
||
|
Avg |
Min |
Max |
|
| Elevation
(metres) |
797 | 370 | 1300 |
| Slope
Gradient (%) |
20 | 0 | 70 |
|
Aspect (degrees) |
176 | 66 | 332 |
| Soil
Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric] |
2 | 0 | 7 |
| Modal
Nutrient Regime
Class |
C | ||
| #
of field plots species was recorded in: |
33 | ||
| Modal
BEC Zone Class |
IDF | ||
|
All BEC Zones (# of stations/zone) species was recorded in |
BG(4), ESSF(1), ICH(1), IDF(20), PP(2) | ||
|
Source:
Klinkenberg 2013
|
|||
Habitat and Range
Mesic to dry roadsides and disturbed areas in the lowland, steppe and montane zones; frequent in S BC; introduced, native range uncertain.Status Information
Synonyms
Synonyms and Alternate Names:
Conyza canadensis var. glabrata (A. Gray) Cronquist
Erigeron canadensis var. glabratus Gray