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

Dulichium arundinaceum (L.) Britton
three-way sedge (threeway sedge)
Cyperaceae (Sedge family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #79666)

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Distribution of Dulichium arundinaceum
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Three-way sedge is a perennial rhizomatous species that is widely found across North America. It is found in almost all states and provinces in the eastern half of the continent (exclusive of Labrador), and in some states and provinces in the west (USDA 2011). In British Columbia, it ranges across the southernmost part of the province--it is encountered frequently in the southwestern corner of the province, but rarely in the southeast. It occurs in wet meadows, lakeshores and streamsides in the lowland, steppe and montane zones and will often appear along streams (and in streambeds) that flow through bogs in the Fraser delta, and in ditches in the region. It has distinctive step-like leaves that are 120 degrees apart and are arranged spirally on the stem. View a video of identification of this species, with Tony Reznicek.

Species Information

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Perennial herb from deep-seated rhizomes; stems erect, arising singly, 30-100 cm tall.
Numerous, well-developed, along the stem, the uppermost 3-ranked; upper sheaths often overlapping; blades firm, flat, 4-15 cm long, 2.5-8 mm wide, the lower bladeless.
Inflorescence elongate with numerous, axillary spikes emerging from leaf sheaths, the stalks more or less exserted, the internodes of the axis of the inflorescence about 2 mm long, the spikelets 2-ranked, 7 to 10, 1-2.5 cm long, slender, about 2 mm wide or less; stamens 3; stigmas 2-cleft; bracts 2-ranked, 3-8 mm wide, strongly veined, the tips short-pointed, the margins translucent.
Scales several-nerved, narrow, pointed or long-pointed, 5-8 mm long, rachilla easily disarticulating at maturity; perianth bristles brownish, 5 to 8, 3-8 mm long, with reflexed barbs, persistent; achenes narrowly ellipsoid, more or less flat, yellow, mostly 2.5-3 mm long excluding the short (to 1 mm long) stalks, beaked by the persistent, undivided portion of the styles, surpassed by the perianth bristles.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Late Summer
Fruit/Seed characteristics:
Colour: Brown
Present over the Fall
Source:  The USDA

Habitat / Range

Wet meadows, lakeshores and streamsides in the lowland, steppe and montane zones; frequent in SW BC, rare in SC BC; E to NF and S to FL, MS, TX, WY, ID and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Dulichium arundinaceum

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) 15 261 670
Slope Gradient (%) 0 0 0
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
5 7 8
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: CDF(13), CWH(21), ICH(4)


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 cool temperate & cool mesothermal.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References