Vallisneria

Vallisneria americana

Vallisneria, and water screws and Germanized called Vallisneria is a genus within the family of frog bite plants ( Hydrocharitaceae ). The approximately 14 species grow as submerged aquatic plants in freshwater or brackish water in the subtropics to tropics almost worldwide. Vallisneria spiralis is an invasive plant in some subtropical and tropical regions, such as Hawaii, New Zealand and also in Germany.

• 4.1 Notes and references

Description and autecology

Appearance and leaves

Vallisneria species usually grow as a perennial, rarely annual, herbaceous plants. The upright, short, unbranched stem axis form roots in a body of water. By rhizomes or stolons stocks are formed.

The submerged leaves are arranged all the distributed basal or alternate, spiral or two lines on the stem. The leaves consist of leaf sheath and leaf blade, but are always without petiole. The simple leaf blades are linear or strap- shaped with a Spreitenbasis which merges gradually into the leaf blade, and a blunt to inked top end. It is Parallelnervatur ago with eight to nine veins. The leaf margins are smooth sawn or tiny.

Inflorescences and flowers

Vallisneria species are dioecious getrenntgeschlechtig ( dioecious ). The pendant, zymösen inflorescences are unisexual and have a spathe, which is formed from two fused bracts. The male inflorescences are on a short to very short inflorescence stem and contain many flowers on a central column arranged. The spathe of the male inflorescence is ovoid or broadly lanceolate. The female inflorescences are on a long inflorescence stem, are flutend and contain only one flower. In Florida, Alabama, Mississippi and Central America there are some Vallisneria populations which contain the female inflorescences, instead of only single bloom to 30 flowers. The spathe of the male inflorescence is tubular with two-column top.

The unisexual flowers are triple double perianth. The three sepals are tiny, which in the male flowers two are greater than the third. The three transparent petals are longer than the sepals. The male flowers are released from the inflorescence and float to the water surface. The tiny male flowers contain three free stamens, three of which are fertile, or a discount of up to two staminodes. The anthers are spherical. The pollen grains spread as monads. The three free pen each end in a two-column scar. Three carpels are under a constant, unilocular ovary adherent, which is cylindrical or narrowly triangular - cylindrical. There are many ovules available. Pollination is in the water by the male flowers about freely drifting.

Fruit and seeds

After fertilization, the Blütenstandsschäfte wrap on helical and ensure that the ripening fruit are held just below the water surface. The narrow cylindrical or narrowly triangular, cylindrical fleshy and berry-like, cylindrical to ellipsoidal, serrated fruit capsules open into irregular parts and contain many seeds. The bare elongated or spindle- shaped seeds contain starch and a straight embryo with one seed leaf ( cotyledon ).

Systematics and occurrence

Vallisneria species occur in the subtropics to tropics almost worldwide.

The genus Vallisneria was erected in 1753 by Carl Linnaeus in Species Plantarum, 2, S. 1015. Vallisneria spiralis L. is the type species. Vallisneria The genus name honors the Italian botanist Antonio Vallisneri ( 1661-1730 ). Synonyms for Vallisneria L. are: Maidenia Rendle, Physkium Lour ..

The genus Vallisneria belongs to the subfamily Hydrilloideae within the family Hydrocharitaceae.

There are about 14 (2011 ) ( 8-26 ) Vallisneria species:

• Vallisneria americana Michx. ( Syn: Vallisneria spiralis var americana ( Michx. ) Torr, Vallisneria neotropicalis Vict. . ): It occurs in many parts of North America from Canada to Mexico and Central America as well as on the Caribbean Islands.
• Vallisneria anhuiensis XSShen: It occurs only in the Chinese province of Anhui.
• Vallisneria annua SWLJacobs & KAFrank: This annual species is native to northern and central Australia.
• Giant Vallis ( Vallisneria australis SWLJacobs & Les, Syn: Vallisneria spiralis var procera): It occurs in the Australian states of New South Wales, Queensland, Victoria, South Australia, Western Australia and Tasmania.
• Vallisneria caulescens FMBailey & F.Muell. It occurs in northern Australia.
• Vallisneria denseserrulata ( Makino ) Makino: It occurs to flow and standing water in southern and eastern China and the Japanese island of Honshu.
• Vallisneria erecta SWLJacobs: It occurs only in the north-eastern Queensland.
• Vallisneria longipedunculata XSShen: It occurs only in the Chinese province of Anhui.
• Narrow Vallis, dwarf or giant Vallis Vallis ( Vallisneria nana R.Br., Vallisneria gracilis FMBailey, Vallisneria gigantea Graebn. ): It comes from the Philippines to Australia to New Caledonia before.

• Vallisneria natans ( Lour. ) H.Hara ( Syn: Physkium natans Lour, Vallisneria physkium Juss ex Spreng nom illeg, Vallisneria spiraloides Roxb, Vallisneria minor Ito, Vallisneria spiralis f minor ( Ito ) Makino, Vallisneria. .. .. . spiralis var subulispatha Makino, Vallisneria asiatica Miki, Vallisneria asiatica var biwaensis Miki, Vallisneria asiatica var higoensis Miki, Vallisneria subulispatha ( Makino ) Koidz. , Vallisneria biwaensis ( Miki ) Ohwi, Vallisneria higoensis ( Miki ) Ohwi, Vallisneria gigantea var. higoensis ( Miki ) Kitam, Vallisneria natans var biwaensis ( Miki ) H.Hara, Vallisneria natans var higoensis ( Miki ) H.Hara, Vallisneria americana var biwaensis ( Miki ) Lowden ): It is widely used in almost the whole of Asia to Australia.
• Vallisneria rubra ( Rendle ) Les & SWLJacobs: 2008 This newly described species is found only in the north-western Australia.
• Vallisneria spinulosa SZYan: She comes to standing water only in the Chinese provinces of Guangxi, Hubei, Hunan and Jiangsu.
• Vallisneria spiralis L. ( Vallisneria jacquinii Savi Savi michelii Vallisneria, Vallisneria linnet Bercht. & J.Presl, Vallisneria jacquiniana Spreng., Vallisneria me eliana Spreng., Vallisneria pusilla Barbieri ex Bertol. , Vallisneria aethiopica Fenzl, Vallisneria numidica Pomel, Vallisneria spiralis subvar. jacquinii ( Savi ) Nyman, Vallisneria spiralis subvar. michelii ( Savi ) Nyman, Vallisneria spiralis var pusilla ( Barbieri ex Bertol. ) Nyman, Vallisneria spiralis f aethiopica ( Fenzl ) T.Durand & Schinz, Vallisneria spiralis var numidica ( Pomel ) Maire & Weiller ): It is widespread in Eurasia, and also occurs in South Africa.
• Vallisneria triptera SWLJacobs & KAFrank: It occurs only in northern Australia.

The trivial name of the species prevails through many trade names diversity and confusion. An example is Giant Vallis, which is sensibly not to use, as it is for Vallisneria australis and Vallisneria gigantea, which is just a synonym of Vallisneria nana, used / was.

Use

As an ornamental plant in ponds and aquariums for example, the screw Vallis ( Vallisneria spiralis ), the American Water screw ( Vallisneria americana) and Vallisneria nana be used. There are also some elite forms with variations in leaf color, which are used as aquarium plants.

Swell

• Robert R. Haynes: Hydrocharitaceae. In: Flora of North America Editorial Committee ( eds.): Flora of North America North of Mexico. Volume 22: Magnoliophyta: Alismatidae, Arecidae, Commelinidae ( in part), and Zingiberidae. Oxford University Press, New York et al 2000, ISBN 0-19-513729-9: Vallisneria - text Registered as printed work. (Section Description, systematics and distribution )
• Qingfeng Wang, Youhao Guo, Robert R. Haynes, C. Barre Hellquist: Hydrocharitaceae. In: Wu Zheng -yi, Peter H. Raven, Deyuan Hong (eds.): Flora of China. Volume 23: Acoraceae through Cyperaceae. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 2010, ISBN 978-1-930723-99-3: Vallisneria. S. 99 - the same text online as well as printed work. (Section Description, systematics and distribution )
• Abdul Ghafoor :: Vallisneria. In: Flora of Pakistan. ( Description section )
• H. R. Coleman: Vallisneria. In: Western Australian flora., 2008. (Section Description )
• SWL Jacobs include: entry to New South Wales Flora Online. ( Description section )
• Donald H. Les, Surrey WL Jacobs, Nicholas P. Tippery, Lei Chen, Michael L. Moody, Maike Wilstermann - Hildebrand: Systematics of Vallisneria ( Hydrocharitaceae ). In: Systematic Botany. Volume 33, Issue 1, 2008, pp. 49-65. doi: 10.1600/036364408783887483 ( section systematics)