- Potamogeton
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Potamogeton 
Potamogeton perfoliatus Scientific classification Kingdom: Plantae (unranked): Angiosperms (unranked): Monocots Order: Alismatales Family: Potamogetonaceae Genus: Potamogeton
L.Species 80-100, see text
Potamogeton is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name 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 potamos (river) and geiton (neighbor).[1][2]
Contents
Morphology
Potamogeton species may be large or very small. Plants are sometimes annuals but are often perennial and typically produce rhizomes 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 stolons from the rhizome. The leaves are alternate, which contrasts with the closely related genus Groenlandia 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 leathery.
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. At least 26 hybrids have been observed in the British Isles alone.[2]
Species include:
- P. acutifolius
- P. alpinus
- P. amplifolius
- P. angustifolius
- P. berchtoldii
- P. clystocarpus
- P. coloratus
- P. compressus
- P. crispus
- P. diversifolius
- P. epihydrus
- P. filiformis
- P. foliosus
- P. friesii
- P. gayi
- P. gramineus
- P. illinoensis
- P. lucens
- P. natans
- P. nodosus
- P. obtusifolius
- P. pectinatus
- P. perfoliatus
- P. polygonifolius
- P. praelongus
- P. pusillus
- P. richardsonii
- P. robbinsii
- P. rutilus
- P. trichoides
- P. zosteriformis
Ecology
Potamogeton species are found worldwide in many aquatic ecosystems. They are important as food and habitat for animals.[2][3] Most species are not weedy, but a few can become troublesome, such as curly-leaf pondweed (Potamogeton crispus).[4]
References
Categories:- Potamogeton
- Aquatic plants
- Alismatales genera
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