General:
Perennial, tufted herb from long, creeping rhizomes; stems triangular, with rough edges, 30-120 cm tall, equalling the leaves.

Leaves:
Sheaths tight, short; blades flat, well distributed along the stem, 3-7 mm wide, the lower ones slightly reduced.

Flowers:
Spikes 3 to 10, the terminal 1 to 3 short-stalked, with male flowers, the lower spikes 2 to 7, with mostly female flowers and often several male flowers at the tops, with long stalks, 3-14 cm long, spreading or drooping; bracts subtending the spikes leaflike, sheathless, the lower ones longer than the inflorescence, the upper ones reduced.

Fruits:
Perigynia egg-shaped, 2-3.6 mm long, 1.3-2.3 mm wide, brownish-green, 3-angled, the angles rounded, smooth to somewhat wrinkled, marginally 2-nerved, entire or minutely bidentate; female scales egg-shaped, shorter or longer than the perigynia, often shortly awn-tipped, brownish-red, with lighter 3-nerved centres and translucent margins, often whitish at the tips; stigmas 2; achenes lens-shaped, granular, 1.1-1.5 mm long.

Notes:
Although Standley (1985) treated this taxon as a variety of C. aquatilis, we have not. To do so, it would require a similar treatment for many other taxa in our region now recognized at the species level. Also, for practical reasons, merging C. sitchensis, a community dominant, with C. aquatilis would result in resource managers naming the community after the latter.

Source:  The Illustrated Flora of British Columbia