''Potamogeton trichoides'' is a species of

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

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.

Description

Hairlike pondweed is an aquatic perennial that dies back each winter into a large number of asexually produced resting bodies called turions. There are no rhizomes. It produces slender, cylindrical or slightly compressed, branching stems usually less than a metre in length but occasionally up to 2 m. The submerged leaves are long and very narrow, typically 16–80 mm long and 0.3–1 mm wide, with the midrib occupying up to 70% of the width of the leaf near the base. They are rigid and green turning darker with age. There are no floating leaves. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is a short spike of 3–5 flowers arising from the water on a slender peduncle. This species readily hybridizes with several other species of ''

Potamogeton ''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'' ...

'' including ''P. berchtoldii'' (''P.'' × ''franconicus'' G.Fisch.), ''P. pusillus'' (''P.'' × ''grovesii'' Dandy & G.Taylor) and ''P. compressus'' (''P.'' × ''ripoides'' Baagøe). Hairlike pondweed is diploid, with 2n=26

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

s. Hairlike pondweed is one of the more distinctive fine-leaved pondweeds due to the characteristically stiff leaves dominated by the midrib and open but tightly rolled stipules. However, it tends to be rarer than other fine-leaved species and often grows in mixed beds with other fine-leaved water plants such as ''P. pusillus'' and ''Zannichellia palustris'', so it may be overlooked.

Taxonomy

''Potamogeton trichoides'' (trichoides = 'hairlike') was named by the German botanists

Adelbert von Chamisso Adelbert von Chamisso (; 30 January 178121 August 1838) was a German poet and botanist, author of ''Peter Schlemihl'', a famous story about a man who sold his shadow. He was commonly known in French as Adelbert de Chamisso (or Chamissot) de Bonc ...

and

Diederich Franz Leonhard von Schlechtendal Diederich Franz Leonhard von Schlechtendal (27 November 1794, Xanten – 12 October 1866, Halle) was a German botanist. He studied in Berlin, in 1819 becoming curator of the Royal Herbarium. He was a professor of botany and director of the Bo ...

in 1827. Hairlike pondweed is one of the fine-leaved pondweed clade (series Graminifolii), and related to similar species such ''P. pusillus''.

Distribution

''Potamogeton trichoides'' is native to the western Palaearctic and Africa. It occurs in northern Europe (Austria, Britain, Czech Republic, Denmark, France, Germany, Italy (including Sicily), Norway, Spain, Sweden, Switzerland, Poland, Russia, the Baltic States), North Africa (Morocco, Algeria, Tunisia, Libya, Egypt), eastern and southern Africa (South Africa, Tanzania, Uganda, Zimbabwe). There are outlying populations in the Canaries, the Caucasus, and Russia east of the Urals.

Ecology and conservation

Hairlike pondweed grows predominantly in standing water including ponds, lakes, ditches, canals and slow-flowing rivers and streams. It is usually restricted to calcareous water of rather high conductivity and is tolerant of high nutrient levels. It is often an early succession species, colonising newly created habitats such as ditches and flooded gravel pits, but sometimes is abundant in alkaline, low altitude lakes. It often grows with other nutrient tolerant macrophytes such as ''Myriophyllum spicatum'', ''Potamogeton crispus'', ''P. pusillus'' and ''Ranunculus circinatus''. In Britain, hairlike pondweed is thought to be stable or possibly increasing. However, it is placed in various threat categories in parts of its range, for example it is Vulnerable in the Czech Republic, and Germany (although still widespread along all major river systems there), and Critically Endangered in Switzerland.

Cultivation

''Potamogeton trichoides'' is not in general cultivation, and is of little garden merit.

References

{{Taxonbar, from=Q10546830 trichoides