Juncus mertensianus Bong.
Mertens' rush
Juncaceae (Rush family)

Introduction to Vascular Plants


© Bryan Kelly-McArthur     (Photo ID #74333)


E-Flora BC Static Map

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

Species Information

Perennial herb from elongated rhizomes; stems arising singly, erect, 15-25 cm tall.
Located on the lower part of the stem, nearly circular in cross-section, tapered, the early leaves stiff, with prominent complete cross-walls; sheaths open, with rounded, ear-shaped lobes.
Numerous, in single, terminal, hemispheric heads; perianth segments dark brown, 3-4.5 mm long, pointed, the inner about the same length or shorter than the outer; stamens 6; anthers 0.6 mm long, shorter than the filaments; involucral bract solitary, short, equalling or exceeding the inflorescence.
Capsules, cylindrical to egg-shaped, rounded or with small depressions, slightly shorter than the perianth segments; seeds barrel-like, about 0.4 mm long, lacking tail-like appendages.

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.

USDA Species Characteristics

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


Ecological Framework for Juncus mertensianus

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)
1793 100 2468
Slope Gradient (%)
14 0 85

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

180 0 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
5 0 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

AT(20), BAFA(19), CMA(9), CWH(3), ESSF(123), ICH(3), IDF(1), IMA(7), MH(11), MS(1), SBS(2), SWB(4)

Habitat and Range

Moist to wet meadows, pond edges, grassy streamsides, snowbed sites and open boggy forests from the montane to alpine zones; common throughout BC; amphiberingian, N to AK, YT and NT, E to AB and S to SD, NM, AZ and CA; Japan.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Juncus columbianus Coville
Juncus mertensianus subsp. mertensianus
Juncus mertensianus var. columbianus (Coville) F.J. Herm.
Juncus slwookoorum S.B. Young