''Zannichellia palustris'', the horned pondweed, is a plant found in fresh to

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

s in the United States (especially in the

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...

), 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. The species epithet ''palustris'' is Latin for "of the marsh" and indicates its common

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

. A diploid, its

chromosome number Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectivel ...

was confirmed as 2''n'' = 24.Norio Tanaka, Yu Ito, Ruriko Matsuyama and Koichi Uehara (2007) Chromosome numbers of ''Zannichellia'' L. (Zannichelliaceae) in Japan. Bulletin of the National Museum of Nature and Science. Series B 33: 133-136

References

Potamogetonaceae Aquatic plants Flora of Europe Flora of North America Flora of temperate Asia Plants described in 1753 Taxa named by Carl Linnaeus {{monocot-stub