Shoreline Plants  

 
Species: Dulichium arundinaceum (L.) Britton, dulichium, three-way sedge
Family: Cyperaceae

This tall, perennial grass-like herb has stems that arise singly or in small patches from creeping rootstocks. The leaves are arranged in three vertical rows along the upper stem, giving the plant a symmetrical appearance. This can be observed by looking straight down on the plant. Dulichium is a member of the sedge family, which includes the more common genus Carex. Unlike Carex, the stems of Dulichium are hollow and only vaguely, if at all triangular. This plant is common in coastal areas and less common inland. It occurs in wet meadows, bogs, and in the shallow water of stream and lake margins.
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Leaf: The narrow, alternate grass-like leaves are 3-8 mm wide and 2-9 cm long. They are rather stiffly pointed upwards and spirally arranged in 3 rows around the upper part of the stem. The lower leaves are reduced to bladeless, sometimes brown-tinged shealths.

Stem:  Stems are round or sometimes slightly triangular. They are hollow between the leaf nodes, jointed, and range from 30 cm to 1 m in height. They arise from extensive underground rhizomes.

Flower: Flowers are arranged as 7 to 10 spikelets growing from the bases of the upper leaves. These spikelets are 0.5-2.5 cm long with several greenish scales arranged in 2 rows along a central stalk. Scales conceal inconspicuous bisexual flowers.

Fruit: The flattened, linear, yellow achenes are 2.5-3 mm long and are tipped with spines. 6-9 minutely barbed bristles attached to the base of each achene.

Root: Fibrous and arising from rhizomes.

Propagation: Seeds, and can spread by rhizomes. 

Importance of plant: The achenes are eaten by waterfowl. Dulicium's rhizomatous growth my also help stabilize shorelines. 

Distribution: North America. In Washington, dulichium is more common west of the Cascades and in wooded areas of central and eastern Washington.

Habitat: Wet meadows, bogs, margins of lakes, ponds, and streams.

May be confused with: Grasses and other members of the sedge family. Grasses have leaves in 2 vertical rows instead of 3. Sedges of the genus Carex have unisexual flowers with the female flowers enclosed in a sac (perigynium), whereas dulichium flowers are bisexual, lack a perigynium, and flowers are arranged in 3 vertical rows on the stalk.

Photographs: Dulichium arundinaceum closeup, dulichium growing along Lake margin

Line Drawings: None available


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