Vallisneria

Wallisnerias are real aquatic plants ( hydrophytes ) adapted to life in rivers or lakes.

This is a plant with a long thin creeping rhizome .

Stems with rosette leaves strengthened in the soil with the help of long shoots at some distance from the parent plant. The leaves are bright green or reddish, entirely submerged in water, ribbon-like linear or lanceolate in basal rosettes, less often at the base of heart-shaped ^[3] , soft, smooth-edged or finely serrated at the apex at the edge. Sometimes the stem developed branching, and the leaves are alternate, less often whorled, supplied with axillary scales ^[3] . There are species of various sizes, some with spirally twisted leaves ( Vallisneria spiralis ( Vallisneria spiralis L. )). Paunch parallel. The length of the leaves is up to 1 m; in most species, the leaves, reaching the surface of the water, creep along it and flow over it. On this basis, Vallisneria can be distinguished from arrowheads . Arrowheads at first glance are very similar to these plants, but their underwater leaves never creep along the surface.

Wallisnerias are dioecious , male plants appear on some plants, female flowers on others. The flowers are small, inconspicuous, or rather large, with a perianth that catches the eye, mostly protruding above the surface of the water; single or assembled in half-umbrellas , covered with two coalescent bracts, forming a single sheet cover; several inflorescences leave from one bosom of leaf. The perianth of two circles (outer and inner, sometimes painted petals in white) ^[3] . The method of pollination is hydrophilic . Wallisnerias are extremely interesting in their flowering biology. Single pistillate flowers are carried to the surface of water on long flexible peduncles , with a tubular cover (spathe) of accrete bracts . After pollination, the peduncle twists spirally and draws the pollinated flower under water, where the ripening of the fetus takes place. Staminate flowers (with two — three stamens ) are collected in spike-like bunches, under a film cover. After maturation, they detach from the plant, float to the surface of the water and pollinate the female organs. Pollination occurs as a result of direct contact of the stamens of floating male flowers with stigmas of pistillate flowers. The pestle is formed from 2–15 accreted carpels . The ovary is inferior, single-knotted or falsely multiferrimental, cylindrical with many ovules . The stigmas are as much as the carpels ^[3] .

In addition to seed propagation, vallisneria grow vegetatively very quickly. On the shoots , creeping over the surface of the soil or buried in its thickness, buds are formed, after some time turning into tiny daughter plants, which, in turn, rooted in the soil, also emit the layers for the formation of new plants. Reproducing in this way, in a short time, the valisneria at the bottom of rivers and lakes form rich individuals, but poor in species with dense thickets of plants (underwater meadows), firmly interconnected by shoots.

The genus unites only submerged aquatic plants (hydrophytes).

The plant is common in freshwater bodies of the tropics and subtropics of the Western and Eastern Hemispheres, some species have advanced to the temperate zone .

In Russia (on the Lower Don and the Lower Volga , in Ciscaucasia and in the Far East ), one species grows - Vallisneria spiral ( Vallisneria spiralis L. ).

Use

Vallisneria has long attracted the attention of aquarists. They are the most popular aquarium plants , perfectly adapted to life in water. Vallisneria leaves reach 50-70 cm in length and are very beautiful, especially in high aquariums screens. Plants are planted in a group of nutrient soil on the back and middle plans, as well as in the corner of the aquarium.

Conditions of detention

Wallisneria are considered to be unpretentious in content, they withstand rather significant temperature fluctuations, do not impose special requirements on the chemical composition of water, and grow well in both natural and artificial light.

Lighting 0.5 W / L. Water: 24–28 ° C, dH up to 15 ° C, pH 6-7.5. (R. Riel, H. Bensh recommend KN 5-12 ° ^[4] ).

The bright green leaves of Vallisneria are original, but sometimes aquarists are not satisfied with the fact that the densely overgrown aquarium is completely obscured by the upper parts of the leaves floating in the water. In this case, it is necessary to reduce the number of bushes, after thinning the thickets. But in no case can not cut the leaves, which sometimes make amateur aquarists. Wallisneria is quite tenacious, but the leaves at the cut sites will turn yellow and begin to rot.
It should be noted another feature of this plant: the plant does not like excess copper . This trace element can get into the aquarium with drugs that kill algae ( algaecides ) or mollusks . Some substances used, for example, to treat oodinia , also contain copper sulphate , so if the sick fish were treated in an aquarium where the valisneria was growing, it could die. There is evidence that the use of domestic antibiotic " Bicillin-5 " for the treatment of certain fish diseases has a negative impact on the condition of aquarium plants, in particular on Barclaya longifolia , Cardamine lyrata , Vallisneria spiralis L. ^[5] . Therefore, it is necessary to use this drug with great care and, of course, not to use it to disinfect newly acquired plants. The plant also dies from the presence of iron oxide (rust) in the water, which must be taken into account by the owners of a frame aquarium with steel corners.

Reproduction

Vallisneria is propagated by layering formed on a creeping shoot. In favorable conditions, one plant of Vallisneria can produce up to 50 new bushes per year. Since the vallyseries rapidly multiply vegetatively, in an aquarium culture each species is represented mainly by plants of the same sex.

Experimental studies were carried out at Perm State Technical University , which confirmed the possibility of using higher aquatic plants in the process of biological treatment of urban wastewater to reduce the content of nitrogen and phosphorus salts in them. It was established that as a result of using Vallisneria spiralis L. plants in the tertiary settling tank at a biomass density of 7 g / dm³, contact time of 240 minutes and a discharge of 6 m³ / day per 1 m³ of structures, the maximum removal efficiency from the effluent is: ammonium nitrogen - 66 %, nitrate nitrogen - 34%, nitrite nitrogen - 27.0%, phosphate - 41.0%.

The genus was described in 1753 by C. Linnaeus and the honor of the Italian botanist Antonio Vallisneri ^[6] (1661-1730) was named.

In 1982, the genus underwent revision by R. Louden ^[7] , as a result of which only three types remained in it:

• Vallisneria americana Michx. - Vallisneria is American . In the literature, all references to Vallisneria spiralis f. tortifolia refer to this species. Synonyms : Vallisneria spiralis f. americana , Vallisneria asiatica , Vallisneria gigantea , Vallisneria neotropicalis , Vallisneria biwaensis , Vallisneria natans .
• Vallisneria nana R.Br. - Vallisneria dwarf . Synonym for Vallisneria gracilis .
• Vallisneria spiralis L. - Vallisneria spiral .

In 2008, D. Les and others reconsidered the systematics of the Vallisneria, including several new species ^[8] .

According to the information of The Plant List database, the genus includes 14 species ^[9] :

• Vallisneria americana Michx. (1803) - American Vallisneria
• Vallisneria anhuiensis XSShen (2001) - Anhui Wallisneria
• Vallisneria annua SWLJacobs & KAFrank (1997)
• Vallisneria australis SWLJacobs & Les (2008) - Wallisneria Southern
• Vallisneria caulescens FMBailey & F.Muell. (1888)
• Vallisneria densiserrulata ( Makino ) Makino
• Vallisneria erecta SWLJacobs (2008)
• Vallisneria longipedunculata XSShen (2000)
• Vallisneria nana R.Br. (1810)
• Vallisneria natans ( Lour. ) H.Hara (1974) - Wallisneria floating
• Vallisneria rubra ( Rendle ) Les & SWLJacobs (2008) - Vallisneria red
• Vallisneria spinulosa SZYan (1982)
• Vallisneria spiralis L. (1753) typus ^[10] - Valisneria spiral
• Vallisneria triptera SWLJacobs & KAFrank (1997) - Vallisneria three-winged

• Sheremetyev I.I. Botany of the aquarium. Full illustrated encyclopedia. - M. — Donetsk: Eksmo - SKIF, 2004. - p. 307-308. - ISBN 966-8076-37-0 .
• Zolotnitsky NF Amateur Aquarium. - M .: TERRA, 1993. - ISBN 5-85255-405-7 .
• Polonsky V.D. Aquarium plants. - M .: Aquarium-Print, 2005. - p. 78-81. - ISBN 5-98435-161-7 .
• Mayevsky PF Flora of the middle zone of the European part of Russia. - 10th ed. - M .: Tov-in scientific publications KMK, 2006. - p. 20, 61.
• Kalinina E. V. Removal of biogenic elements in the process of biological purification of urban wastewater by higher aquatic plants // Proceedings of the Perm State Technical University: Actual problems of the road-transport complex. Environmental protection. - Perm: Perm. state tech. University Press , 2007. - P. 230—244 .

• Wallisneria // Great Soviet Encyclopedia : [in 30 t.] / Ch. ed. A. M. Prokhorov . - 3rd ed. - M .: Soviet Encyclopedia, 1969-1978. (Checked November 1, 2009)