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The cowpea (''Vigna unguiculata'') is one of several species of the widely cultivated genus ''Vigna''. Four subspecies are recognised, of which three are cultivated (more exist, including ''V. textilis'', ''V. pubescens'', and ''V. sinensis''): Cowpeas are one of the most important food legume crops in the semiarid tropics covering Asia, Africa, southern Europe, and Central and South America. A drought-tolerant and warm-weather crop, cowpeas are well-adapted to the drier regions of the tropics, where other food legumes do not perform well. It also has the useful ability to fix atmospheric nitrogen through its root nodules, and it grows well in poor soils with more than 85% sand and with less than 0.2% organic matter and low levels of phosphorus. In addition, it is shade tolerant, so is compatible as an intercrop with maize, millet, sorghum, sugarcane, and cotton. This makes cowpeas an important component of traditional intercropping systems, especially in the complex and elegant subsistence farming systems of the dry savannas in sub-Saharan Africa.〔Blade, 2005〕 In these systems the haulm (dried stalks) of cowpea is a valuable by-product, used as animal feed. Research in Ghana found that selecting early generations of cowpea crops to increase yield is not an effective strategy. Francis Padi from the Savannah Agricultural Research Institute in Tamale, Ghana, writing in ''Crop Science'', suggests other methods such as bulk breeding are more efficient in developing high-yield varieties. According to the USDA food database, the leaves of the cowpea plant have the highest percentage of calories from protein among vegetarian foods. == Taxonomy and etymology == ''Vigna unguiculata'' is a member of the ''Vigna'' (peas or beans) genus.〔(【引用サイトリンク】title=COWPEA.NET – Main – TaxonomyAndRelatedSpecies )〕 Unguiculata is Latin for "with a small claw", which reflects the small stalks on the flower petals.〔Top 100 Food Plants By Ernest Small page 104〕 All cultivated cowpeas are found within the universally accepted ''V. unguiculata'' subspecies ''unguiculata'' classification, which is then commonly divided into four cultivar groups: ''Unguiculata'', ''Biflora'', ''Sesquipedalis'', and ''Textilis.''〔SINGH, B. B., MOHAN, D. R., DASHIELL, K. E. & JACKAI, L. E. N. (1997) ''Advances in Cowpea Research, ''IITA, Ibadan Nigeria, International Institutre of Tropical Agriculture〕〔 Some well-known common names for cultivated cowpeas include Lesera/ Dangbodi (লেছেৰা/ ডাংবডি) in Assamese, black-eye pea, southern pea, yardlong bean, catjang and Crowder Pea.〔 The classification of the wild relatives within ''V. unguiculata'' is more complicated, with over 20 different names having been used and between 3 and 10 subgroups described.〔〔Theoretical and Applied Genetics May 1999, Volume 98, Issue 6-7, pp 1104–1119 Genetic relationships among subspecies of Vigna unguiculata (L.) Walp. based on allozyme variation R. S. Pasquet〕 The original subgroups of ''stenophylla'', ''dekindtiana and'' ''tenuis ''appear to be common in all taxonomic treatments, with the earlier described variations ''pubescens ''and'' protractor'' being raised to sub species level by a 1993 charactisation.〔〔This appears to be one of the latest taxonomical classifications〕 The first written reference using cowpea appeared in 1798 in the United States.〔 The name was most likely acquired due to their use as a fodder crop for cows.〔3 Cowpea Michael P. Timko Jeff D. Ehlers Philip A. Roberts http://www.faculty.virginia.edu/timko/pdfs/Timko%20et%20al%20%282007%29%20Chapter%203%20Cowpea.pdf〕 The common name of black-eyed pea, used for the unguiculata cultivar group, describes the presence of a distinctive black spot at the hilum of the seed. Black-eyed peas were first introduced to the southern states in the United States and some early varieties had peas squashed closely together in their pods, leading to the other common names of southern pea and crowder-pea.〔 Sesquipedalis in Latin means "foot and a half long", and this subspecies which arrived in the United States via Asia is characterised by unusually long pods, leading to the common names of yardlong bean, asparagus bean and Chinese long-bean. In West Africa the plant is named niebe, wake or ewa. 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「Cowpea」の詳細全文を読む スポンサード リンク
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