Potamogeton perfoliatus | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Alismatales |
Family: | Potamogetonaceae |
Genus: | Potamogeton |
Species: | P. perfoliatus |
Binomial name | |
Potamogeton perfoliatus | |
Synonyms [2] | |
|
Potamogeton perfoliatus (claspingleaf pondweed, [3] perfoliate pondweed, [4] redhead grass [5] ) 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.
Perfoliate pondweed grows from a robust creeping perennial rhizome, intermittently producing round stems up to 3 m long. [6] The submerged leaves are oval and translucent, with no stalk, 20–115 mm long and 7–42 mm wide, clasping the stem (perfoliate), a flat apex, and 5-12 veins on either side of the midrib. [6] They vary considerably in colour and may be bright green, dark green, yellowish, olive or brownish. [6] There are no floating leaves. The stipules are rather delicate and usually fall off quite soon after the new leaf has unfurled. The insignificant flowers are produced between June and September. [7] Fruits are 4 mm across, olive green in colour.
Two subspecies have been described. Subspecies perfoliatus occurs in the Old World. In North America, populations on the eastern seaboard and the Gulf States are considered to be subsp. bupleuroides. [8] Since many pondweeds, including P. perfoliatus, vary naturally in response to growing conditions, [6] it is possible that these variants are ecotypes rather than genuine subspecies. The related P. richardsonii was formerly considered a subspecies of P. perfoliatus, but is now classed as a separate species. [9]
Like most other broadleaved pondweeds, perfoliate pondweed is tetraploid, with 2n=52. [10]
Over much of its range, perfoliate pondweed is unlikely to be confused with any other pondweed species except perhaps P. praelongus. In North America it could be confused with P. richardsonii, but the latter has stipules that disintegrate to persistent fibres even on the lower part of the stem, whereas those of P. perfoliatus disintegrate entirely. [9]
However, perfoliate pondweed regularly hybridises with other Potamogeton species including P. crispus (P. × cooperi(Fryer) Fryer), P. gramineus (P. × nitensWeber), P.lucens (P. × salicifoliusWolfg.), P. alpinus (P. × prussicusHagstr.), P. berchtoldii (P. × mysticusMorong), P. wrightii (P. × anguillanusKoidz.), P. maackianus (P. × leptocephalusKoidz.), P. alpinus (P. × prussicusHagstr.), P. nodosus (P. × assidensZ. Kaplan, Zalewska-Gałosz et M. Ronikier), P. richardsonii (P. × absconditusZ. Kaplan, Fehrer & Hellq.), P. epihydrus (P. × versicolorZ. Kaplan, Hellq. and Fehrer) and P. praelongus (P. × cognatusAsch. & Graebn.). [2] [6] The first three of these are quite common. [6] A triple hybrid, P. gramineus × lucens × perfoliatus (P. × torssandrii(Tiselius) Dörfler), is also known. [10] Many of these hybrids are perennial and long-lived, sometimes occurring in the absence of one or even both parents. Therefore, care should be taken with identification of unusual specimens.[ citation needed ]
Potamogeton perfoliatus (perfoliate meaning that the leaf encircles the stem) was one of the original species named by Linnaeus in Species Plantarum (1753).[ citation needed ]
DNA analysis indicates that P. perfoliatus is one of the broad-leaved pondweed clade (section Potamogeton) and is probably most closely related to P. richardsonii. [11]
Potamogeton perfoliatus has a broad global distribution, occurring in all continents except South America and Antarctica. It has been recorded from Asia (Afghanistan, India, Indonesia (Sumatra), Japan, Kazakhstan, Korea, Kyrgyzstan, Mongolia, Pakistan, Russia, Tajikistan, Uzbekistan), Australia, [12] North America (Eastern and SE USA), [13] Europe south to Spain, Central Italy and the Balkans and including Scandinavia, Britain, Ireland and Iceland, [8] North Africa (Algeria, Tunisia, Egypt), [8] the Near and Middle East. It is widespread in lakes and rivers in the British Isles and Ireland, [14] and is common in much of Eurasia and North America, but has a more scattered distribution towards the southern edge of its range.[ citation needed ]
P. perfoliatus grows in a wide range of freshwater habitats including lakes, rivers and streams, large ponds, canals and larger drains and ditches. It does not tolerate drying out, and the most robust plants tend to occur in >1 m water depth. [6] Unlike most other broad-leaved pondweeds it is reasonably tolerant of water flow and so can use running waters to a significant extent. It is not especially sensitive to water chemistry provided that the water remains reasonably clear and is not too base-poor, occurring in such diverse habitats as exposed Scottish lochs and lowland fenland rivers. However, at high nutrient concentrations it is vulnerable to shading from phytoplankton and epiphytic algae [15] [16] and filamentous algae. [16] It may also grow in brackish or estuarine habitats, notably in Chesapeake Bay. [17] [18] However, elevated salt concentrations have a negative effect on both growth and flowering. [19]
Waterbirds, fish, [17] [20] water beetles and caddis larvae [21] can all be important grazers of perfoliate pondweed, reducing its biomass or even eliminating it locally.[ citation needed ]
Perfoliate pondweed is less threatened than other broadleaved pondweeds, but it is listed as Vulnerable in Spain [22] and the Netherlands [23] and Endangered in Flanders. [24] There are ongoing efforts to restore populations in Chesapeake Bay, where this was formerly a co-dominant species. [25] [26] [27]
Perfoliate pondweed is the commonest of the so-called Magnopotamion group of pondweeds. These are a characteristic floristic component of the protected Habitats Directive habitat Type 'Natural eutrophic lakes with Magnopotamion'. [28]
Perfoliate pondweed is not widely cultivated, which is perhaps surprising as it is not ecologically demanding and is an attractive plant. In common with other pondweeds of this group it roots poorly from stem cuttings and is best propagated by division of the rhizomes. It is easy to grow in a garden pond or even in a barrel, but unlike some other submerged plants needs to be able to root in a suitable substrate such as sand or aquatic compost. Keeping nutrient levels low helps to prevent smothering by algae and more invasive aquatic plants. [17] Plants being established should be weighted down initially to allow them to root, and benefit from being planted among other aquatic plants that can act as a 'nursery'. [26] Transplants have a high survival rate once established. [26]
P. perfoliatus may also be established from seed, which should be sown on a suitable substrate in shallow water. The seed should be left uncovered, or covered only with a minimal amount of substrate to hold the seed in place and allow root development, as seed buried more than 1 cm deep either does not germinate or the seedlings die. [27] The seed typically germinates within about 10 days. [27]
Although it is possible to grow perfoliate pondweed in fish ponds, it would be vulnerable to fish predation initially, so should be protected during establishment.[ citation needed ]
The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. The roughly 110 known species are divided over six genera. The largest genus in the family by far is Potamogeton, which contains about 100 species.
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 natans, commonly known as broad-leaved pondweed, floating pondweed, or floating-leaf pondweed, is an aquatic species in the genus Potamogeton native to quiet or slow-flowing freshwater habitats throughout the Holarctic Kingdom.
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 pusillus is a species of aquatic plant known by the common names small pondweed, lesser pondweed or least pondweed. It occurs in standing and slow-flowing freshwater habitats throughout the Northern Hemisphere.
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 vaginata, commonly called sheathed pondweed, big sheathed pondweed or large-sheathed pondweed is a water plant species that grows in fresh and brackish water in Europe, Northern Asia and North America. Sheathed pondweed is rare, but is not in the 2012 IUCN Red List.
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 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 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.