E-Flora BC: Electronic Atlas of the Flora of British Columbia

Carex pachystachya Cham. ex Steud.
thick-headed sedge (chamisso sedge)
Cyperaceae (Sedge family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #79684)

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Distribution of Carex pachystachya
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Species Information

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Perennial, tufted herb from fibrous roots; stems triangular, with blunt edges, 20-50 cm tall, exceeding the leaves.
Sheaths tight; blades flat, 2-4 mm wide, borne on the lower 1/3 of the stem.
Spikes 4 to 12, aggregated into a dense head, 1-2.5 cm wide, unstalked, with both female and male flowers, the female ones towards the tips; bracts subtending the spikes sheathless, reduced, inconspicuous.
Perigynia egg-shaped, 3-4 mm long, 1-1.5 mm wide, dark green to dark brown, the margins winged nearly to the bases, the upper 1/2 fringed with teeth, lightly several-nerved on the back, with faint nerves or nerveless below, the beaks shallowly bidentate, up to 1 mm long, narrowly margined and toothed below; female scales elliptical, chestnut-brown to dark brown, with slightly lighter midribs, somewhat shorter and narrower than the perigynia; stigmas 2; achenes lens-shaped, 1.1-1.5 mm long.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Late Spring
Fruit/Seed characteristics:
Colour: Brown
Present from Spring to Summer
Source:  The USDA

Habitat / Range

Mesic to wet sites in all vegetation zones; common throughout all but NE BC; amphiberingian, N to AK, YT and NT, E to SK and S to CO, UT, NV and CA; NE Asia.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Carex pachystachya

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




Elevation (metres) 20 1307 2610
Slope Gradient (%) 0 17 300
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
17 186 346
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 4 7
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: AT(7), BAFA(1), CWH(14), ESSF(37), ICH(6), IDF(6), IMA(2), MS(2), SBPS(5), SBS(10)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Carex festiva var. gracilis Olney
Carex festiva var. pachystachya (Cham. ex Steud.) Bailey
Carex macloviana subsp. pachystachya (Cham. ex Steud.) Hult╬śn
Carex macloviana var. pachystachya (Cham. ex Steud.) Knkenth.
Carex multimoda Bailey
Carex pachystachya var. gracilis (Olney) Mackenzie
Carex pachystachya var. monds-coulteri L. Kelso
Carex pyrophila Gandog.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References