Potamogeton is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of aquatic, mostly freshwater, plants of the family Potamogetonaceae

Potamogetonaceae

The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. There are roughly 120 species spread across six genera in the Potamagetonaceae...

. Most are known by the common name

Common name

A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed (Elodea canadensis). The genus name means "river neighbor", originating from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 potamos (river) and geiton (neighbor).

Morphology

Potamogeton species may be large or very small. Plants are sometimes annuals but are often perennial and typically produce rhizome

Rhizome

In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

s which are the common over-wintering form. Many species also produced specialised overwintering buds called turions which may be borne on the rhizome, on the stem or on stolon

Stolon

In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...

s from the rhizome. The leaves are alternate, which contrasts with the closely related genus Groenlandia

Groenlandia

Groenlandia is a genus of aquatic plants of the family Potamogetonaceae....

where the leaves are opposite or whorled.

In many species, all the leaves are submerged and in these cases the leaves are typically thin and translucent. Some species, especially in ponds and very slow moving waters, have floating leaves which tend to be more leather

Leather

Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

y.

Diagnostic of most species of Potamogeton is the presence of a delicate membranous sheathing scale at the leaf axil. This may be wholly attached, partly attached or free of the leaf and it may have inrolled margins or appear as a tube. The flowers, which are often overlooked are composed of 4 rounded segments borne in a spike.

Taxonomy

Potamogeton species are found throughout the world where there is standing or running water. There are estimated to be around 90 species but hybridisation provides an added complexity to the taxonomy

Taxonomy

Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...

. At least 26 hybrids have been observed in the British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

 alone.

Species include:

• P. acutifolius
• P. alpinus
  Potamogeton alpinus
  Potamogeton alpinus is a species of aquatic plant known by the common names alpine pondweed and red pondweed. It is native to much of the Northern Hemisphere, including Eurasia, Greenland, Canada, and northern parts of the United States. It grows in water bodies such as ponds, lakes, marshes, and...
  
  
• P. amplifolius
  Potamogeton amplifolius
  Potamogeton amplifolius, commonly known as largeleaf pondweed or broad-leaved pondweed, is an aquatic plant of North America. It grows in water bodies such as lakes, ponds, and rivers, often in deep water....
  
  
• P. angustifolius
• P. berchtoldii
• P. clystocarpus
  Potamogeton clystocarpus
  Potamogeton clystocarpus is a rare species of flowering plant in the pondweed family known by the common name Little Aguja pondweed. It is endemic to Texas in the United States, where it is known only from one river canyon in Jeff Davis County. There is a single population of the aquatic plant in...
  
  
• P. coloratus
  Potamogeton coloratus
  Potamogeton coloratus L. or Fen Pondweed, is an aquatic species in the genus Potamogeton. It is found in shallow peaty acid water and fens.-Description:...
  
  
• P. compressus
• P. crispus
• P. diversifolius
  Potamogeton diversifolius
  Potamogeton diversifolius is a species of aquatic plant known by the common names waterthread pondweed and diverse-leaved pondweed. It is native to most of the United States, as well as sections of southwestern Canada and northern Mexico, where it grows in water bodies such as ponds, lakes,...
  
  
• P. epihydrus
  Potamogeton epihydrus
  Potamogeton epihydrus is a species of aquatic plant known by the common name ribbonleaf pondweed. It is native to much of North America, where it grows in water bodies such as ponds, lakes, ditches, and slow-moving streams. This is a perennial herb producing a narrow, compressed stem branching to a...
  
  
• P. filiformis
• P. foliosus
  Potamogeton foliosus
  Potamogeton foliosus is a species of aquatic plant known by the common name leafy pondweed. It is native to nearly all of North America and parts of Central America, where it grows in water bodies such as ponds, lakes, ditches, and slow-moving streams. This is a perennial herb growing from a dense,...
  
  
• P. friesii
• P. gayi
• P. gramineus
  Potamogeton gramineus
  Potamogeton gramineus is a species of aquatic plant known by the common name variableleaf pondweed. It is native to much of the Northern Hemisphere, where it grows in water bodies such as ponds, lakes, bogs, and streams. It may be found elsewhere as an introduced species. This is a perennial herb...
  
  
• P. illinoensis
• P. lucens
  Potamogeton lucens
  Potamogeton lucens or Shining Pondweed, is an aquatic species in the genus Potamogeton. It is found in slow moving fresh water, found locally in the south, mid and East of England, almost rare in the rest of Great Britain.-Description:...
  
  
• P. natans
  Potamogeton natans
  Potamogeton natans L. is an aquatic species in the genus Potamogeton native to quiet or slow-flowing freshwater habitats throughout the Holarctic Kingdom....
  
  
• P. nodosus
  Potamogeton nodosus
  Potamogeton nodosus is a species of aquatic plant known by the common name longleaf pondweed. It is native to Eurasia and the Americas, where it is widespread and can be found in water bodies such as ponds, lakes, ditches, and streams. This is a perennial herb producing a thin, branching stem...
  
  
• P. obtusifolius
  Potamogeton obtusifolius
  Potamogeton obtusifolius is an aquatic plant in the genus Potamogeton. It grows mainly in eutrofic lakes and ponds, rarely in brackish water. Species occurs primarily in Central Europe, British Isles, Fennoscandia and eastern North America....
  
  
• P. pectinatus
  Potamogeton pectinatus
  Stuckenia pectinata , commonly called fennel pondweed or sago pondweed, and sometimes called ribbon weed....
  
  
• P. perfoliatus
  Potamogeton perfoliatus
  Potamogeton perfoliatus L. is an aquatic species in the genus Potamogeton occurring in both quiet and flowing freshwater or brackish-water habitats in Central and North America, Eurasia, Africa and Australia.-Description:The leaves are all submerged, oval, translucent, with no stalk, up to 8cm...
  
  
• P. polygonifolius
  Potamogeton polygonifolius
  Potamogeton polygonifolius L. or Bog Pondweed, is an aquatic species in the genus Potamogeton. It is found in shallow peaty acid water and bog pools.-Description:...
  
  
• P. praelongus
  Potamogeton praelongus
  Potamogeton praelongus, commonly known as White-stem Pondweed, is an aquatic plant with stout, rusty-spotted rhizomes. It is relatively easy to distinguish from other Potamogeton species by the leaves clasping around a zig-zagging stem and persistent, whitish stipules.-External links:*****...
  
  
• P. pusillus
  Potamogeton pusillus
  Potamogeton pusillus is a species of aquatic plant known by the common name small pondweed. It has a Circumboreal distribution, occurring throughout the northern Northern Hemisphere. It grows in water bodies such as ponds, lakes, ditches, vernal pools, and slow-moving streams...
  
  
• P. richardsonii
  Potamogeton richardsonii
  Potamogeton richardsonii is a species of aquatic plant known by the common name Richardson's pondweed. It is native to much of northern North America, including all of Canada and the northern and western United States. It grows in water bodies such as ponds, lakes, ditches, and streams...
  
  
• P. robbinsii
  Potamogeton robbinsii
  Potamogeton robbinsii, commonly known as Robbins' Pondweed, is a North American perennial herb.It is found in "deep to shallow, quiet, often muddy waters of lakes, ponds, and rivers."...
  
  
• P. rutilus
• P. trichoides
• P. zosteriformis
  Potamogeton zosteriformis
  Potamogeton zosteriformis is a species of aquatic plant known by the common names flatstem pondweed and eel-grass pondweed. It is native to much of northern North America, including most of Canada and the northern United States. It grows in water bodies such as ponds, lakes, and slow-moving streams...
  
  

Ecology

Potamogeton species are found worldwide in many aquatic ecosystems. They are important as food and habitat for animals. Most species are not weedy, but a few can become troublesome, such as curly-leaf pondweed (Potamogeton crispus).