Page authors: Don Knoke, David Giblin
Ruppia maritima
beaked ditch-grass, spiral ditch-grass, western ditch-grass

Distribution: Occurring along the coast and east of the Cascades crest in Washington, where saline; Alaska to California, inland throughout Canada and the United States to the Atlantic Coast.

Habitat: Coastal in saline or brackish water, inland in ponds, ditches, and lakes.

Flowers: July - August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Water


Aquatic, submersed, herbaceous perennials, the stems filiform and branching, up to 8 dm. long.


Leaves mostly alternate, up to 12 cm. long and scarcely 0.5 mm. broad; stipules sheathing for 5-15 mm., the free tips 1-2 mm. long.


Flowers on short spikes enclosed in the sheathing leaf bases of the upper leaves, usually 2 flowers per spike; flowers naked, usually consisting of 2 stamens and 4 pistils, one stamen below and one above the pistils; peduncles greatly elongating and often coiled in fruit, becoming 3-30 cm. long.


Fruits ovoid and symmetrical to strongly asymmetrical, 1.5-3 mm. long.

Accepted Name:
Ruppia maritima L.
Publication: Sp. Pl. 1: 127. 1753.

Synonyms & Misapplications:
Ruppia cirrhosa (Petagna) Grande [FNA22]
Ruppia maritima L. var. obliqua (Schur) Asch. & Graebn. [Peck]
Ruppia maritima L. var. rostrata Agardh [Peck]
Ruppia occidentalis S. Watson [Abrams]
Additional Resources:

PNW Herbaria: Specimen records of Ruppia maritima in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Ruppia maritima checklist entry.

OregonFlora: Ruppia maritima information.

E-Flora BC: Ruppia maritima atlas page.

CalPhotos: Ruppia maritima photos.

USDA Plants: Ruppia maritima information.

20 photographs:
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