''Potamogeton friesii'', known as flat-stalked pondweed,
[ or Fries' pondweed,]genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''Potamogeton''. It grows mainly in mesotrophic to eutrophic
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplan ...
rivers, lakes, ponds and ditches, rarely in brackish
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 estu ...
water. It occurs in North America, Europe, western Asia and a few scattered locations elsewhere in Asia.
Description
Flat-stalked pondweed grows annually from turions and seed, producing branching plants with slender, flattened stems that are well-branched. The submerged leaves are long, rather grass-like, sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
, and translucent. The leaf tips are mucronate (i.e. with the midrib extending out of the leaf, giving a pointed appearance).[ Abundant turions are produced along the stem, especially in autumn as the plant disintegrates.
Flat-stalked pondweed could be confused with other fine-leaved pondweeds within its range, especially '']Potamogeton obtusifolius
''Potamogeton obtusifolius'', known as blunt-leaved pondweed, is an aquatic plant in the genus ''Potamogeton''. It grows mainly in mesotrophic to eutrophic lakes, ponds and ditches, rarely in brackish water. It occurs primarily in Central Europe ...
''[ but potentially also '' P. pusillus''. The combination of open stipules, rounded tips to the leaves, dense flower spikes and a tendency to produce a mass of bushy growth at the surface all help to distinguish this plant, but use of a botanical key or flora is recommended.
''Potamogeton friesii'' is diploid, with 2n=26.][
Two hybrids of ''Potamogeton friesii'' have been described, with P. crispus (''P''. × ''lintonii'' Fryer) and P. acutifolius (''P''. × ''pseudofriesii'' Dandy & G.Taylor).][
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Taxonomy
Flat-stalked pondweed was first described in 1847 by the Austrian botanist Franz Josef Ruprecht
Franz Josef Ruprecht (1 November 1814 – 4 April 1870) was an Austrian-born physician and botanist active in the Russian Empire, where he was known as Frants Ivanovič Ruprekht (russian: link=no, Франц Ива́нович Ру́прехт).
...
.[ The specific name ''friesii'' commemorates the Swedish mycologist and botanist Elias Magnus Fries.][ It is related to other fine-leaved pondweeds such as ''P. obtusifolius'', ''P. foliosus'' and ''P. pusillus''.][
]
Distribution
''Potamogeton friesii'' occurs predominantly in North America (Canada, northern USA),[ Europe (Scandinavia, Germany, Poland, British Isles, NE and central France, Belarus, Ukraine, European Russia, Pyrenees, Carpathians),][ There are isolated populations in southern Europe (Corsica, N Italy, Balkans) and in Asia (N China, Russia, Japan, Kazakhstan, Tajikistan).][
]
Ecology and conservation
In Britain, ''P. friesii'' occurs in a range of standing water habitats including ponds, ditches, canals,[ and is tolerant of ]eutrophication
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...
, especially in rivers.[ Like other fine-leaved pondweeds, ''P. friesii'' probably benefits from a certain amount of disturbance to suppress competing vegetation.
Flat-stalked pondweed has suffered local declines and is thought to be extinct in the Czech Republic,][ and is Endangered in Switzerland,][ and Germany.][ It is considered to have declined in Britain, but is still widespread,][ and was listed as Near Threatened in 2002.][ A more recent assessment for England only][ reassessed its status as Vulnerable, reflecting ongoing population declines. However, in the Netherlands it is considered least concern.][
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Cultivation
Flat-stalked pondweed is not presently in cultivation. Although its wide ecological tolerance suggests it may not be difficult to grow, it would probably require a deeper substrate than is usual in most ornamental ponds. It is also likely to compete poorly with other pond plants.
References
External links
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{{Taxonbar, from=Q159925
friesii