| Potamogeton ×griffithii | |
|---|---|
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Alismatales |
| Family: | Potamogetonaceae |
| Genus: | Potamogeton |
| Species: | P. ×griffithii |
| Binomial name | |
| Potamogeton ×griffithii A. Bennett | |
Potamogeton × griffithii is a hybrid pondweed between Potamogeton alpinus and Potamogeton praelongus . It occurs in oligotrophic, moderate alkalinity lakes.
Potamogeton × griffithii is a sterile hybrid pondweed between red pondweed Potamogeton alpinus and long-stalked pondweed Potamogeton praelongus. It occurs in clear, oligotrophic, low to moderate alkalinity lakes. It was discovered in 1882 in Llyn Anafon, North Wales by J.E. Griffith, a Victorian botanist, and was named after him by the noted pondweed expert Arthur Bennett.
Although intermediate in character between the parents, Potamogeton x griffithii is unlikely to be confused with either. It has long, branched stems to at least 1.7 m [1] and probably longer, growing from slender perennial rhizomes. The translucent mid to deep green leaves are typically between 120 and 240 mm long, occasionally reach 330 mm and are 10–25 mm wide and hooded at the tip. [1] The leaves are sessile, sometimes slightly clasping the stem but shortly petiolate leaves may also be present. The stipules are persistent, open, colourless with a milky tinge, and opaque when dry. [1] Floating leaves may be produced and are relatively narrow, 85-105 x 13–25 mm. Turions are absent. The inflorescences are 10–20 mm long and have inconspicuous greenish flowers on robust peduncles 45–190 mm long. [1] Fruits are not produced. [1]
Potamogeton × griffithii is relatively easy to identify. It is larger than P. alpinus, and the branching habit immediately distinguishes the two. [1] The leaf tip is also more distinctly hooded. The leaves are relatively longer than P. praelongus and P. perfoliatus, and mostly do not clasp the stem. The stems are also markedly more slender than P. praelongus and do not develop the characteristic 'zigzag' pattern caused by the stem changing the angle of growth at each node.
Potamogeton × griffithii is a rare hybrid. As well as its type locality in Wales, it has also been found in a lake in the north of Ireland, and in two lakes in western Scotland. [1] In North America, it has been recorded from three locations in the USA, all in Wisconsin, and in Canada (Alberta). [2]
In Llyn Anafon, Potamogeton x griffithii grows in clear, oligotrophic water with some basic influence, 0.75-3.2 m deep, among beds of Chara virgata [3] and in shallower water, in a more diverse community including Nitella opaca, N. translucens, Utricularia minor , Juncus bulbosus, Isoetes lacustris and Callitriche brutia var. hamulata . One of the parents, Potamogeton alpinus, grows in the inflow stream, but P. praelongus has never been recorded in or near the lake. It is likely that the beds of P. × griffithii here have been established for centuries, perhaps even millennia. P. praelongus has not been recorded at any of the British and Irish sites where P. × griffithii grows. [1] [3]
Potamogeton × griffithii is classified as Vulnerable by both the British [4] and Welsh [5] Vascular Plant Red Lists due to the low number of sites in which it occurs.
Potamogeton × griffithii is not in general cultivation, though like both of its parents it is an attractive plant. A patch has been established in a wildlife pond in Bangor University's Treborth Botanic Gardens, where it grows well on a sandy substrate in about 1 m depth. In common with other pondweeds of this group it roots poorly from stem cuttings and is best propagated by division of the rhizomes. Good water quality is needed to reduce the risk of turbid water or growth of blanket weed.
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 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.
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.
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 × 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.