What is "zannichellia palustris"

Pondweed \Pond"weed`\, n. (Bot.) Any aquatic plant of the genus Potamogeton, of which many species are found in ponds or slow-moving rivers.

Choke pondweed, an American water weed ( Anarcharis Canadensis, syn. Elodea Canadensis.) See Anacharis.

Horned pondweed, the Zannichellia palustris, a slender, branching aquatic plant, having pointed nutlets.

Zannichellia palustris, the horned pondweed, is a plant found in fresh to brackish waters in the United States (especially in the Chesapeake Bay), Europe, Asia, Australasia, and South America. It is recognizable by its long, thread like leaves, and "stringy" appearance. Its roots are also long and tendril-like, and its seeds bear a distinctive horned shape, hence the common name. Chromosome number was confirmed as 2n = 24 in Japan.