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''Amaranthus'', collectively known as amaranth, is a cosmopolitan genus of annual or short-lived perennial plants. Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental plants. Most of the species from ''Amaranthus'' are summer annual weeds and are commonly referred to as pigweed.〔Bensch et al. (2003). Interference of redroot pigweed (''Amaranthus retroflexus''), Palmer amaranth (''A. palmeri''), and common waterhemp (''A. rudis'') in soybean. Weed Science 51: 37-43.〕 Catkin-like cymes of densely packed flowers grow in summer or autumn. Approximately 60 species are recognized, with inflorescences and foliage ranging from purple and red to green or gold. Members of this genus share many characteristics and uses with members of the closely related genus ''Celosia''. "Amaranth" derives from Greek 〔(【引用サイトリンク】title=Henry George Liddell, Robert Scott, A Greek-English Lexicon, ἀμάραντος )〕 (''amarantos''), "unfading," with the Greek word for "flower," ἄνθος (''anthos''), factoring into the word's development as "amaranth." The more accurate "amarant" is an archaic variant. == Taxonomy == ''Amaranthus'' shows a wide variety of morphological diversity among and even within certain species. Although the family (Amaranthaceae) is distinctive, the genus has few distinguishing characters among the 70 species included. This complicates taxonomy and ''Amaranthus'' has generally been considered among systematists as a "difficult" genus. Formerly, Sauer (1955) classified the genus into two subgenera, differentiating only between monoecious and dioecious species: ''Acnida'' (L.) Aellen ex K.R. Robertson and ''Amaranthus''.〔 Although this classification was widely accepted, further infrageneric classification was (and still is) needed to differentiate this widely diverse group. Currently, ''Amaranthus'' includes three recognized subgenera and 70 species, although species numbers are questionable due to hybridization and species concepts.〔Judd et al. (2008). Plant Systematics: A Phylogenetic Approach, Third Edition. Sinauer Associates, Inc. Sunderland, MA〕 Infrageneric classification focuses on inflorescence, flower characters and whether a species is monoecious/dioecious, as in the Sauer (1955) suggested classification.〔 A modified infrageneric classification of ''Amaranthus'' was published by Mosyakin & Robertson (1996) and includes three subgenera: ''Acnida'', ''Amaranthus'', and ''Albersia''. The taxonomy is further differentiated by sections within each of the subgenera. 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「Amaranth」の詳細全文を読む スポンサード リンク
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