Submersed Plants

 
Species: Vallisneria americana Michx., tapegrass, water celery
Family: Hydrocharitaceae

Tapegrass is an almost completely underwater perennial herb with long, narrow, green to sometimes reddish, ribbon-like leaves growing from rhizomes. Tapegrass can be distinguished from similar plants by a prominent stripe, called a midrib, running down the center of each leaf. The presence of coiled, corkscrew-like flower stalks can also help identify this plant. Although tapegrass was introduced to the Pacific Northwest for fish and wildlife habitat purposes, it appears to cause none of the problems associated with invasive introduced plants like Eurasian watermilfoil.

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Leaf: The mostly submersed leaves are flat, thin, and ribbon-like (to 3 m long and 2.5 cm wide) and end in a blunt tip. The leaf tips are sometimes floating. The distinctive midrib consists of many parallel veins bounded by clear outer zones. Each bundle of leaves arises from a short stem buried in the sediment.

Stem: The short, slender stems arise from joints on the creeping, horizontal rhizomes.

Flower: Male and female flowers are on separate plants. Tiny male flowers (1 mm) produced at the plant base are released to float on the water surface. Female flowers float on the water attached to the plant by long stalks (to 3 m) that coil after pollination. Pollination takes place when male flowers float into female flowers. Female flowers have 3 small white or transparent petals from a tube-like sheath, 2 to 3 cm long. 

Fruit: Cylindrical, slightly curved pods, 5 to 10 cm long. Each contains many tiny seeds in a gelatinous material. Seeds are released into the water when fruits decay.

Root: Slender, fibrous roots arise from horizontal rhizomes.

Propagation: Seeds, rhizomes. 

Importance of plant: Leaves, fruits, and rootstocks are excellent food for waterfowl. Also provides habitat for fish and invertebrates. Has been used to monitor pollution levels in eastern rivers.

Distribution: Native to eastern North America. Introduced to several Washington lakes, but generally does not cause problems. Also in Mexico, Central America, Asia, Australia, and the Caribbean.

Habitat: Ponds, lakes, and quiet streams at depths of 1 to 4 m. 

May be confused with: Bur-reeds (Sparganium spp.), submersed leaves of duck potato (Sagittaria spp.), northern mannagrass (Glyceria borealis), and wild rice (Zizania aquatica), which all can have long, ribbon-like underwater leaves, but do not have the distinctive midrib or the coiled fruit stalk of tapegrass.

Photographs: Closeup of the coiled flower stalk of Vallisneria americana

Line Drawings: Vallisneria americana


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