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

Juncus supiniformis Engelm.
spreading rush (hairyleaf rush)
Juncaceae (Rush family)

Introduction to Vascular Plants

© Adolf Ceska  Email the photographer   (Photo ID #25749)

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Distribution of Juncus supiniformis
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Species Information

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Perennial, loosely tufted herb from short rhizomes; stems erect or spreading, 15-75 cm long, often submerged, rooting at the nodes, often also viviparous (producing plantlets in the inflorescence).
Located on the lower part of the stem, nearly circular in cross-section, tapered, the early leaves threadlike, flaccid, other leaves firm and erect, usually submerged, with prominent, complete crosswalls, sheaths open, with short, rounded, ear-shaped lobes.
Inflorescence terminal, 5-15 cm long, in 2 to 6 heads of 3 to 10 flowers, the branches ascending; perianth segments dark brown or reddish-brown, 3-4.5 mm long, narrowly lanceolate, pointed, or short-awned, the inner about the same length as the outer; stamens 6; anthers 0.7-1 mm long, shorter than the filaments.
Capsules, narrowly cylindrical, pointed, 1-1.5 mm longer than the perianth segments, black; seeds spindle-shaped, about 0.6-0.7 mm long, lacking tail-like appendages.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Shallow water, wet mud, lakeshores and open peat bogs in the lowland and montane zones; common in BC west of the Coast-Cascade Mountains; N to AK and S to CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Juncus supiniformis

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) 40 205 750
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 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: BWBS(1), CDF(4), CWH(17)


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 subalpine boreal & cool mesothermal.

Synonyms and Alternate Names

Juncus oreganus S. Watson

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References