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

Glyceria x occidentalis (Piper) J.C. Nels.
western mannagrass
Poaceae (Grass family)

Introduction to Vascular Plants
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E-Flora BC Static Map
Distribution of Glyceria x occidentalis
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Species Information

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Perennial grass from rhizomes; stems erect to more or less decumbent, hollow, up to 70-150 cm tall.
Sheaths somewhat flattened, apparently smooth, but minutely rough, closed at the base but open above; blades 4-8 (12) mm wide, flat or folded, minutely rough to more or less pimpled or just minutely rough on the upper surfaces, minutely rough on the lower surfaces; ligules pointed, entire to irregularly jagged, smooth or sparsely hairy, 7-12 mm long.
Inflorescence a narrow panicle 20-50 cm long, the branches mostly ascending or sometimes spreading; spikelets mostly 6- to 13-flowered, linear, 15-22 mm long; glumes broad, the margins lightly jagged and more or less fringed with fine hairs at the tips, the lower ones about 1.5 mm long, the upper ones at least twice as long; lemmas 5-6 mm long, prominently 7-nerved, finely rough on the nerves and over the back, slightly jagged and more or less fringed with fine hairs at the blunt tips; paleas shorter than the lemmas; stamens 3; anthers 1.1-1.6 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Marshes, lakeshores and wet meadows and forests in the lowland zone; rare in coastal SW BC; S to ID and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Glyceria x occidentalis

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) 1030 1030 1030
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 7 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: IDF(2), SBPS(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.

Synonyms and Alternate Names

Glyceria occidentalis (Piper) J.C. Nels.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References