翻訳と辞書 Words near each other ・ TracFone Wireless ・ Tracfort ・ Trachea ・ Trachea (moth) ・ Trachea atriplicis ・ Trachea auriplena ・ Tracheal agenesis ・ Tracheal collapse ・ Tracheal cytotoxin ・ Tracheal deviation ・ Tracheal intubation ・ Tracheal rings ・ Tracheal tube ・ Tracheal tumor ・ Trachealis muscle ・ Tracheid ・ Tracheitis ・ Trachelacanthus ・ Tracheliastes ・ Tracheliastes polycolpus ・ Trachelidae ・ Trachelipodidae ・ Trachelipus ・ Trachelipus aegaeus ・ Trachelipus ater ・ Trachelipus camerani ・ Trachelipus difficilis ・ Trachelipus dimorphus ・ Trachelipus gagriensis ・ Trachelipus mostarensis Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Tracheid ： ウィキペディア英語版 Tracheid Tracheids are elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts. Tracheids are one of two types of tracheary elements, vessel elements being the other. Tracheids, unlike vessel elements, do not have perforation plates. All tracheary elements develop a thick lignified cell wall, and at maturity the protoplast has broken down and disappeared. The presence of tracheary elements is the defining characteristic of vascular plants to differentiate them from non-vascular plants. The two major functions that tracheids may fulfill are contributing to the transport system and providing structural support. The secondary walls have thickenings in various forms—as annular rings; as continuous helices (called helical or spiral); as a network (called reticulate); as transverse nets (called scalariform); or, as extensive thickenings except in the region of pits (called pitted). Tracheids provide most of the structural support in softwoods, where they are the major cell type. Because tracheids have a much higher surface to volume ratio compared to vessel elements, they serve to hold water against gravity (by adhesion) when transpiration is not occurring. This is likely one mechanism that helps plants prevent air embolisms. ==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「Tracheid」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.