leafy thistle (elk thistle)
Asteraceae (Aster family)
Introduction to Vascular Plants
Species Information
General:
Biennial or short-lived perennial herb from a taproot; stems erect, thick, fleshy, ribbed, soft, spreading-hairy, simple, 0.2-1.0 m tall.
Leaves:
Basal and stem leaves linear-oblanceolate, shallowly to deeply pinnately cut or merely toothed, segments, when present, egg-shaped, margins of the segments with slender spines, sparsely woolly above and below, the uppermost leaves ascending, extending beyond and often obscuring the compact group of heads.
Flowers:
Heads discoid, 1-5, in a terminal cluster; involucres egg-shaped, 2-4 cm tall; involucral bracts sparsely hairy, lanceolate to narrowly egg-shaped, outer ones tapering to a slender 2-3 mm spine, inner ones abruptly sharp-pointed, unarmed, sometimes irregularly-margined at the tip; disk flowers white, sometimes pale pink, 20-25 mm long.
Fruits:
Achenes 4-5.5 mm long, light brown with darker, fine parallel lines and a narrow yellowish apical rim; pappus tawny, 22-30 mm, exceeding the corollas by 1-10 mm.
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:
Late Spring
Fruit/Seed characteristics:
Colour: Brown
Present over the Summer
Source: The USDA
Ecology
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) |
972 | 779 | 1205 |
| Slope
Gradient (%) |
6 | 0 | 26 |
|
Aspect (degrees) |
201 | 99 | 270 |
| Soil
Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric] |
5 | 4 | 6 |
| Modal
Nutrient Regime
Class |
D | ||
| #
of field plots species was recorded in: |
5 | ||
| Modal
BEC Zone Class |
BWBS | ||
|
All BEC Zones (# of stations/zone) species was recorded in |
BWBS(2), ESSF(1), PP(1), SBS(1) | ||
|
Source:
Klinkenberg 2013
|
|||
Habitat and Range
Moist to mesic meadows and forest openings in the montane and subalpine zones; infrequent in BC east of the Coast-Cascade Mountains; N to YT and S to WY.Status Information
Synonyms
Synonyms and Alternate Names:
Cirsium foliosum var. minganense (Victorin) B. Boivin
Taxonomic Keys
TAXONOMIC KEY TO CIRSIUM
1. Heads small; involucres 1-2 (rarely 2.5) cm tall; plants introduced.
2. Stems distinctly spiny-winged; plants with perfect flowers C. palustre 1. Heads large; involucres more than 2 cm tall; plants native (except C. vulgare).
3. Leaves bristly-spiny above, stems distinctly spiny-winged............ C. vulgare
4. Pappus of mature seeds exceeding the corollas by 1-10 mm.............. C. foliosum
5. Heads large; involucres 3-5 cm tall........... C. drummondii 6. Outer involucral bracts more than 2 mm wide at base, slightly if at all hairy and if so, then mainly marginal.
7. Outer involucral bracts strongly glandular; lowermost leaves deeply pinnately lobed more than 1/2 the width of the blade.............. C. undulatum 6. Outer involucral bracts less than 2 mm wide at base, densely cobwebby.
8. Corollas white or creamy-white, rarely pinkish; involucral bracts greenish............. C. hookerianum
9. Styles exceeding the corollas by at least 3 mm; achenes 5-6.5 mm long; leaves usually lobed more than 1/2 the width of the blade.............. C. edule Source: Illustrated Flora of British Columbia |