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

Agrostis idahoensis Nash
Idaho bentgrass
Poaceae (Grass family)

Introduction to Vascular Plants
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Distribution of Agrostis idahoensis
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Species Information

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Perennial grass from fibrous roots, with scattered shoots; stems 12-35 cm tall.
Sheaths smooth; blades 1-5 cm long, 0.5-2 mm wide, flat, becoming in-rolled; ligules 1-3 mm long, slightly rough on the outside.
Inflorescence open, lanceolate to broadly egg-shaped, at least twice as long as wide, 3-10 (13) cm long, the branches spreading to ascending, the lower ones 1-4 cm long; spikelets broadly separated, sparse; glumes 1.5-2.5 mm long; lemmas 1.2-2 mm long, awnless, the callus hairs to 0.3 mm long; paleas absent or if present, as thin membranes less than 1/4 as long as the lemmas; anthers 0.3-0.5 mm long.
This species is often confused with the larger-panicled A. scabra and the awned A. mertensii.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

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

Habitat / Range

Edges of bog pools, wet meadows, fens and seepage areas in the subalpine and alpine zones, occasionally in ditches and wet sites in the montane zone; infrequent on Vancouver Island, the adjacent mainland and north in the Coast Mountains; N to AK, E to AB and S to NM, AZ and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Agrostis idahoensis

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) 1000 1199 1476
Slope Gradient (%) 0 9 23
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
18 354 270
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 5 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: ESSF(1), IDF(1), MH(2), SWB(1)


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.

Synonyms and Alternate Names

Agrostis bakeri Rydb.
Agrostis borealis Hartm.
Agrostis borealis var. americana (Scribn.) Fernald
Agrostis borealis var. paludosa (Scribn.) Fernald
Agrostis borealis var. recta (Hartm.) B. Boivin
Agrostis clavata Trin.
Agrostis filicumis M.E. Jones
Agrostis idahoensis var. bakeri (Rydb.) W.A. Weber
Agrostis mertensii subsp. borealis (Hartm.) Tzvelev
Agrostis rupestris auct. non All.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References