Zannichellia palustris horned pondweed Zannichelliaceae ZAPA; Bx, br;

 

Zannichellia palustris.Donald Cameron.New England Wild Flower Society.gobotany.newenglandwild org

Zannichellia palustris.Donald Cameron.New England Wild Flower Society.gobotany.newenglandwild org (Accessed 4/2014).

Zannichellia palustris is a submersed monocotyledon, rooted aquatic herb, colonial from rhizomes, rooting at nodes, tendril-like coiled adventitious roots may help anchor plants (Sculthorpe 1985). 

Leaves opposite or apparently in whorls of 3-4, linear, filament-like, to 10 cm x 0.5 mm, 1-veined. 

Flowers axillary, very small, no petals or sepals. 

Fruit an achene to 0.3 cm, plus beak of 0.1 cm, body slightly asymmetric and keeled around margin (like a tiny, short green bean), often in pairs or whorls or 3-4 in axils; blooms and fruits July-Oct. 

Wetland status: OBL. 

Frequency in NYC: Very infrequent. 

Origin: Native. 

Habitat: Fresh, often high nutrient, or brackish water. 

Notes: Seeds and plants eaten by many species of duck (Martin et al. 1951). Widespread in N. America but fossils found in Britain and Western Europe (Sculthorpe 1985).