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

Juncus filiformis L.
thread rush
Juncaceae (Rush family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #85503)

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Distribution of Juncus filiformis
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Species Information

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Perennial herb from elongated rhizomes; stems arising singly, not in dense clusters, round, usually straight, smooth, finely grooved, 15-40 cm tall.
Reduced to small sheaths at the base of the stem; sheaths dull, light brown.
Inflorescence a head-like cluster, with numerous flowers on branches 0.5-3 cm long, appearing as if on the side of the stem, located about halfway between the tip of the involucral bract and the base of the stem; perianth segments pale green or whitish, 3-4 mm long, pointed, subequal; stamens 6; anthers shorter than the filaments; involucral bract 7-20 cm long, cylindrical, resembling a continuation of the stem, subequal to longer than the stem.
Capsules, globe-shaped, slightly shorter than the perianth segments; seeds egg-shaped, 0.4-0.5 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Moist meadows and wet sandy lakeshores from the lowland and steppe to subalpine zones; infrequent throughout BC; circumpolar, N to AK, YT, and NT, E to NF and S to MA, WV, PA, MI, WI, MN, NE, NM, UT, ID and OR; Eurasia, Patagonia.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Juncus filiformis

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) 350 1046 1870
Slope Gradient (%) 0 1 10
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
44 57 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
5 6 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: BG(3), BWBS(2), ESSF(10), ICH(7), IDF(1), MS(1), SBS(2)


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.

Taxonomic and Nomenclatural Links

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General References