Common eelgrass is a perennial (sometimes annual) aquatic rhizomatous species native to the coastlines of North America and Eurasia, where it is found in cooler waters of the North Atlantic and North Pacific; in warmer parts of its range it dies back in the summer (Wikipedia 2012). It is a species of calmer waters in the sublittoral zone (Wikipedia 2012). Common eelgrass co-occurs with Japanese eelgrass (Zostera japonica) from BC south to Oregon, however Japanese eelgrass is found primarily in upper intertidal zones (Green and Short 2003). Common eelgrass is a significant species in coastal waters: "Zostera marina is the dominant species in terms of biomass and habitats on the Pacific coast of North America where it grows in: the shallow waters of the continental shelf, the Gulf of California, coastal lagoons such as San Quintin, Baja California, Mexico and Izembek Lagoon, Alaska, estuaries formed by tectonic processes like San Francisco Bay, and coastal fiords similar to Puget Sound, Washington. It is found along the coast of British Columbia, including the coasts of Vancouver Island and Queen Charlotte Islands (Haida Gwaii) in sheltered bays and coves including Bamfield Harbour and Sooke River. " (Green and Short 2003).

General:
Perennial, aquatic herb from slender rhizomes; stems annual, branching, 100-250 cm long, arising from the rhizome nodes.

Leaves:
Sheaths closed; stem leaves alternate, (2) 3-12 mm wide, 5- to many-veined, up to 120 cm long.

Flowers:
Inflorescence a spike of unstalked male and female flowers alternating in 2 rows, 3-6 cm long; female flowers with ovaries tapering to short styles; male flowers with unstalked anthers.

Fruits:
Nutlets, flasklike, about 4 mm long, the walls translucent, strongly ribbed.

Notes:
Recognition of infraspecific taxa in Z. marina (Brayshaw 1985), based on leaf features, appears to be a meaningless exercise considering the plasticity of these features and the lack of research.

Source:  The Illustrated Flora of British Columbia

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration Source:  The Illustrated Flora of British Columbia

Synonyms and Alternate Names:
Zostera marina var. latifolia Morong
Zostera marina var. stenophylla Asch. & Graebn.
Zostera oregana
Zostera pacifica L.
Zostera stenophylla