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''Azolla pinnata'' is a species of fern known by several common names, including feathered mosquitofern and water velvet. It is native to much of Africa, Asia from China to Japan, India and the Philippines, and parts of Australia. It is an aquatic plant, its frond floating upon the surface of the water. It grows in quiet and slow-moving water bodies, because swift currents and waves break up the plant.〔(Pacific Island Ecosystems at Risk )〕 This is a small fern with a triangular frond measuring up to 2.5 centimeters in length which floats on the water. The frond is made up of many rounded or angular overlapping leaves each 1 or 2 millimeters long. They are green, blue-green, or dark red in color and coated in tiny hairs, giving them a velvety appearance.〔 The hairs make the top surface of the leaf water-repellent, keeping the plant afloat even after being pushed under.〔 A water body may be coated in a dense layer of the plants, which form a velvety mat that crowds out other plants.〔 The hairlike roots extend out into the water.〔 The leaves contain the cyanobacterium ''Anabaena azollae'', which is a symbiont that fixes nitrogen from the atmosphere that the fern can use.〔〔Sood, A., et al. (2005). Indicators of phosphorus deficiency in ''Azolla pinnata'' (Salviniales, Pteridophyta). ''Acta Botanica Hungarica'' 47:1-2 197.〕 This gives the fern the ability to grow in habitats that are low in nitrogen.〔 The plant reproduces vegetatively when branches break off the main axis, or sexually when sporocarps on the leaves release spores.〔(''Azolla pinnata''. ) Nonindigenous Aquatic Species. USGS〕 It is present in New Zealand as an introduced species and an invasive weed that has crowded out a native relative, ''Azolla rubra''.〔 It is a pest of waterways because its dense mats reduce oxygen in the water.〔(''Azolla pinnata''. ) Idaho Agriculture.〕 The weevil ''Stenopelmus rufinasus'' is used as an agent of biological pest control to manage ''Azolla filiculoides'', and it has been found to attack ''A. pinnata'' as well.〔Pemberton, R. W. and J. M. Bodle. (2009). (Native North American Azolla Weevil, ''Stenopelmus rufinasus'' (Coleoptera: Curculionidae), uses the invasive old world ''Azolla pinnata'' as a host plant. ) ''Florida Entomologist'' 92:1 153.〕 Rice farmers sometimes keep this plant in their paddies because it generates valuable nitrogen via its symbiotic cyanobacteria.〔〔 The plant can be grown in wet soil and then plowed under, generating a good amount of nitrogen-rich fertilizer.〔Kaur, H. (Biomass production of ''Azolla pinnata'' R. Br. in contaminated soils of Punjab (India). )〕 The plant has the ability to absorb a certain amount of heavy metal pollution, such as lead, from contaminated water.〔Jain, S. K. (1990).''Azolla pinnata'' R.Br. and ''Lemna minor'' L. for removal of lead and zinc from polluted water. ''Water Research 24:2 177-83.〕 It is 25-30% protein and can be added to chicken feed.〔Basak, B., et al. (2002). (Azolla (''Azolla pinnata'') as a feed ingredient in broiler ration. ) ''International Journal of Poultry Science'' 1:1 29.〕〔Alalade, O. A. and E. A. Iyayi. (2006). (Chemical composition and the feeding value of azolla (''Azolla pinnata'') meal for egg-type chicks. ) ''International Journal of Poultry Science'' 5:2 137.〕 ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Azolla pinnata」の詳細全文を読む スポンサード リンク
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