Potamogeton pusillus | |
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Herbarium specimen from Lower Saxony, Germany | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Alismatales |
Family: | Potamogetonaceae |
Genus: | Potamogeton |
Species: | P. pusillus |
Binomial name | |
Potamogeton pusillus | |
Synonyms [2] | |
Synonymy
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Potamogeton pusillus is a species of aquatic plant known by the common names small pondweed, [3] lesser pondweed [4] or least pondweed. It occurs in standing and slow-flowing freshwater habitats throughout the Northern Hemisphere.
Lesser pondweed is a superficially grasslike herb producing a very slender, branching, somewhat compressed stem, usually less than 70 cm but occasionally up to one metre in length. [5] Nodal glands, if present, are generally poorly developed. The leaves are narrow and linear, translucent, mid or olive green, usually 20–50 mm long × 0.8-1.4 mm wide, but rarely up to 100 mm long and 1.9 mm wide. The midrib often lacks lacunae (transparent areas either side of the midrib) either side of it, and if present, lacunae are restricted to the lower half of the leaf. [5] There are no floating leaves. The stipules are tubular when young, but tend to split with age. [5]
Turions are produced, often in large quantities. In early autumn the entire plant disintegrates into a mass of turions, which act as a means of propagation and as an overwintering mechanism.
The inflorescence is a spike of 3-6 flowers arranged in interrupted whorls.
Like most fine-leaved pondweeds, Potamogeton pusillus is diploid, with 2n=26. [6]
Lesser pondweed can be difficult to distinguish reliably from other fine-leaved pondweeds, especially P. berchtoldii . Hybrids are recorded with Potamogeton octandrus (P. × apertusMiki), P. polygonus (P. × attenuatusHagstr.), P. obtusifolius (P. × saxonicusHagstr.), P. trichoides (P. × grovesiiDandy & G.Taylor), P. berchtoldii (P. × mucronulatus(G.Fisch.) Papch.), P. oxyphyllus (P. × orientalisHagstr.). [2]
Lesser pondweed was one of several pondweeds first named by Linnaeus in his Species Plantarum (1753). The specific epithet pusillus means 'small'.
This is one of a group of rather similar fine-leaved species that also includes P. berchtoldii , P. hillii and P. ochreatus. [7] These are quite morphologically variable plants, often with wide geographical and ecological ranges, which has resulted in a great deal of taxonomic confusion and an unusually large number of synonyms and invalid names (see the taxon box).
Lesser pondweed is widely distributed globally, occurring across most of Europe (including Scandinavia) and North America. [8] [9] It is reported from scattered locations in Central and Southeast Asia and is widespread in China. [10] It is also widespread in South America [1] and Africa. [10] [1]
Lesser pondweed grows in standing or slow-flowing water bodies such as ponds, lakes, ditches, slow-moving streams, and river backwaters. It is a lowland plant and requires calcareous water, with a marked preference for high nutrient levels, and may form extensive beds in favourable situations, growing with other nutrient-tolerant species such as Myriophyllum spicatum and Zannichellia palustris . It is tolerant of turbid water and is a good colonist, often exploiting temporary or disturbed habitats such as livestock drinking ponds, canals and ditches. In lakes it is very tolerant of eutrophication and the resulting competition from phytoplankton and periphyton, and is often one of the last submerged plants to disappear.
Globally, Potamogeton pusillus is listed as Least Concern.There is no evidence of local declines and in many areas it is probably increasing due to eutrophication of freshwater habitats. [11] In many parts of its range it is the commonest fine-leaved pondweed.
Lesser pondweed should not be difficult to grow in a garden pond and its tolerance of poor water quality would be advantageous. However, it is not very ornamental.
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. The genus name means "river neighbor", originating from the Greek potamos (river) and geiton (neighbor).
Potamogeton crispus, the crisp-leaved pondweed, curly pondweed, curly-leaf pondweed or curled pondweed, is a species of aquatic plant (hydrophyte) native to Eurasia but an introduced species and often a noxious weed in North America.
Potamogeton perfoliatus is a perennial aquatic plant in the family Potamogetonaceae occurring in both standing and flowing freshwater habitats. It is widely distributed globally, occurring in all continents except South America and Antarctica.
Potamogeton praelongus, commonly known as whitestem pondweed in North America and long-stalked pondweed in Britain, is a large, perennial aquatic plant in the family Potamogetonaceae. It is widely distributed in lakes and rivers in the northern hemisphere, but is sensitive to poor water quality.
Potamogeton polygonifolius or bog pondweed, is an aquatic plant. It is found in shallow, nutrient-poor, usually acid standing or running water, bogs, fens and occasionally ditches.
Potamogeton coloratus, the fen pondweed, is an aquatic plant in the genus Potamogeton. It is found in shallow peaty calcareous lakes, ponds and ditches, commonly associated with lowland fens.
Potamogeton lucens, or shining pondweed, is an aquatic perennial plant native to Eurasia and North Africa. It grows in relatively deep, still or slow-flowing, calcareous freshwater habitats.
Potamogeton alpinus is a species of perennial aquatic plant known by the common names alpine pondweed and red pondweed. It is widespread in the northern hemisphere in both rivers and lakes with good water quality.
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, ditches, and slow-moving streams. This is a perennial herb producing a very narrow, compressed stem branching to a maximum length around 35 centimeters. It has thin, pointed linear leaves a few centimeters long spirally arranged about the thin stem. The inflorescence is a small spike of flowers emerging from the water surface. Inflorescences also grow on submersed sections of the stem; these are smaller and spherical. It can be difficult to distinguish from similar species of pondweed.
Potamogeton epihydrus is a perennial aquatic plant known by the common names ribbonleaf pondweed and Nuttall's pondweed, and American pondweed in the United Kingdom. It is native to much of North America, where it grows in water bodies such as ponds, lakes, ditches, and slow-moving streams.
Potamogeton gramineus is a species of aquatic plant known by the common name various-leaved pondweed, variableleaf pondweed, grass-leaved pondweed or grassy pondweed, native to the northern hemisphere where it grows in shallow, clean water.
Potamogeton compressus is a species of aquatic plant known by the common names grass-wrack pondweed, flatstem pondweed and eel-grass pondweed.
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, the British Isles, Fennoscandia and eastern North America.
Stuckenia is a genus of flowering aquatic plants. It contains approximately 30 species that grow in shallow water. Pondweed is a common name for plants in this genus.
Potamogeton berchtoldii, common name small pondweed is an aquatic plant.
Potamogeton acutifolius is a European species of aquatic plant in the family Potamogetonaceae, known by the common name sharp-leaved pondweed. It is threatened and declining in at least part of its range.
Potamogeton × griffithii is a hybrid pondweed between Potamogeton alpinus and Potamogeton praelongus. It occurs in oligotrophic, moderate alkalinity lakes.
Potamogeton trichoides is a species of aquatic plant known by the common name hairlike pondweed, native to Europe and western Asia where it grows in calcareous, usually nutrient-rich standing or slow-flowing water.
Potamogeton × angustifolius is a hybrid pondweed between Potamogeton gramineus and Potamogeton lucens, known as long-leaved pondweed. It is widespread in rivers and lakes except where the water is very soft.
Potamogeton friesii, known as flat-stalked pondweed, or Fries' pondweed, is an aquatic plant in the genus Potamogeton. It grows mainly in mesotrophic to eutrophic rivers, lakes, ponds and ditches, rarely in brackish water. It occurs in North America, Europe, western Asia and a few scattered locations elsewhere in Asia.