marsh thistle
Asteraceae (Aster family)
Introduction to Vascular Plants
Species Information
General:
Biennial herb from a fibrous root; stems erect, slender, ribbed, simple or sometimes with ascending branches above, strongly spiny-winged from the winged leaf bases, 0.3-2.0 m tall.
Leaves:
Basal and lower stem leaves narrowly elliptic; middle stem leaves and reduced upper ones lanceolate, pinnately cut to about 1/2 the width of the leaf, the segments narrow, spine-tipped, the bases winged, nearly glabrous to lightly soft-hairy above, lightly to densely long-hairy below.
Flowers:
Heads discoid, several to many, in small, compact clusters terminating the stem or at the ends of branches; involucres egg-shaped to cylindric, 1-1.5 cm tall; involucral bracts sparsely to densely cobwebby, outer ones egg-shaped to lanceolate, often purple-tipped, sticky, usually tapering to a thick, often curved, abruptly sharp-pointed 0.5-1 mm long spine, inner ones progressively longer, unarmed, flat-tipped, pointed; disk flowers purple, 10-12 mm long.
Fruits:
Achenes 2.5-3.5 mm long, straw-coloured; pappus tawny, 9-10 mm long.
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
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) |
916 | 698 | 1104 |
| Slope
Gradient (%) |
10 | 0 | 23 |
|
Aspect (degrees) |
192 | 40 | 260 |
| Soil
Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric] |
4 | 3 | 5 |
| Modal
Nutrient Regime
Class |
C | ||
| #
of field plots species was recorded in: |
8 | ||
| Modal
BEC Zone Class |
ICH | ||
|
All BEC Zones (# of stations/zone) species was recorded in |
ESSF(3), ICH(4), SBS(1) | ||
|
Source:
Klinkenberg 2013
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Habitat and Range
Moist meadows and forest openings in the lowland zone; infrequent throughout BC south of 55degreeN; introduced from Europe.Status Information
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 |
Taxonomic Notes
The Invasive Plant Council of British Columbia lists this species as one of BC's most unwanted species. Visit their web site.
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