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

Catabrosa aquatica (L.) P. Beauv.
Water Whorl Grass (Brookgrass; water whorlgrass)
Poaceae (Grass family)

Introduction to Vascular Plants
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Distribution of Catabrosa aquatica
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Catabrosa aquatica var. aquatica

Species Information

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Perennial grass from rhizomes; stems hollow, erect to decumbent, 10-60 cm tall.
Sheaths sometimes open half their length, sometimes closed to near the summit; blades 2-13 mm wide, flat, narrowed to prowlike tips; ligules 2-8 mm long, minutely more or less rough, jagged to nearly entire.
Inflorescence a panicle, (5) 7-20 cm long; spikelets usually 2-flowered, occasionally only 1-flowered, about 3 mm long; lower glumes 0.7-1.3 mm long, the upper ones 1.5-2.2 mm long; upper florets usually deciduous well before the lower; lemmas 2.5-3 mm long, prominently 3-nerved; rachilla joints usually at least 1 mm long; paleas as long as the lemmas; lodicules about 0.3 mm long; anthers about 1.5 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Wet meadows, streambanks and pond and lake margins in the lowland and montane zones; rare in SW BC (Texada Island where probably introduced) and SE BC (Fernie); circumpolar, E to PQ and S to WI, IA, NE, NM, AZ and NV; Europe.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Catabrosa aquatica

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) 1323 1323 1323
Slope Gradient (%) 12 12 12
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
5 4 5
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
5 5 5
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)


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.

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