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

Glyceria maxima (Hartm.) Holmb.
giant mannagrass (reed mannagrass)
Poaceae (Grass family)

Introduction to Vascular Plants

© Rosemary Taylor  Email the photographer   (Photo ID #42675)

E-Flora BC Static Map
Distribution of Glyceria maxima
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Species Information

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Perennial grass from rhizomes with numerous long shoots; stems erect, hollow, (60) 80-200 (250) cm tall.
Sheaths rough; blades 8-18 mm wide, 30-60 cm long, bright green, smooth below, rough above, with 2 pale brown, triangular spots at the base below, the upper leaves indistinctly cross-wrinkled; ligules 2.5-3.5 mm long, blunt at the tips, slightly jagged with a central spine-shaped tip, the tips 1-2 mm long.
Inflorescence a dense panicle, 10-40 cm long, with 4 to 10 branches at the central panicle nodes, the branches relatively thick, nearly erect to spreading, rough, with the main axis rough; spikelets 7- to 9-flowered, egg-shaped, green or tinged with yellow or violet, 2.5-6.5 mm long and up to about 2.5 mm wide; glumes nearly sharp-pointed, the lower ones 2-3 mm long, the upper ones 3-4 mm long; lemmas prominently 7-nerved, blunt, 2.5-4 mm long; paleas blunt, with wide V-shaped notches, 3-4 mm long, concealed by the lemmas; stamens 3; anthers 1-2 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Brackish tidal marshes, lakeshores and wet meadows in the lowland zone; rare in SW and WC (lower Skeena River) BC; introduced from Eurasia.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Glyceria maxima

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) 0 576 894
Slope Gradient (%) 0 0 0
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
99 98 99
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
6 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: CWH(1), PP(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 maxima subsp. grandis (S. Watson) Hultén
Glyceria maxima var. americana (Torr.) B. Boivin
Glyceria spectabilis Mert. & W.D.J. Koch
Molinia maxima Hartm.
Panicularia grandis (S. Watson) Nash

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References