Juncus filiformis L.
thread rush
Juncaceae (Rush family)

Introduction to Vascular Plants


© Bryan Kelly-McArthur     (Photo ID #85503)


E-Flora BC Static Map

Distribution of Juncus filiformis
Click here to view the full interactive map and legend

Species Information

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.

SourceThe Illustrated Flora of British Columbia


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.


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)
1046 350 1870
Slope Gradient (%)
1 0 10

Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]

57 44 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
6 5 8
Modal Nutrient Regime
# 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)

Habitat and 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.

SourceThe Illustrated Flora of British Columbia