原葉體

原葉體

蕨類的一種綠色心形結構(小配子體),既產生雄配子也產生雌配子。原葉體從一個孢子形成。受精後,形成一個幼小的孢子體;由初生根、初生葉、莖原莖和一個稱為莖足的器官組成。莖足能從配子體吸取養料。一些蕨類植物和針葉植物的小孢子的一個原葉體細胞相當於雌配子體的營養體。

簡介

中文名

原葉體

英文名

prothallium

原葉體原葉體

是蕨類植物有性世代的配子體.含葉綠體,有假根,能獨立生活.其貼地一面生有頸卵器(雌性生殖器)和精子器(雄性生殖器),分別可產生一個卵細胞和多數精子.精子借水遊動到頸卵器中,與那裡的卵細胞結合.合子在頸卵器內發育成胚,再發育成孢子體.

概述

蕨類植物的配子體.微小,大多生活時期較短,無根、莖、葉的分化,僅具假根.其上產生精子器和頸卵器,在有水的條件下完成受精過程.當受精卵分裂發育成胚、幼孢子體長出後,原葉體逐漸枯萎.不同的蕨類其原葉體的形態、大小和營養方式也有差異.如松葉蕨的原葉體呈不規則圓柱狀,埋入土中,無葉綠體,體內具維管組織,有真菌與其共生;石松類的原葉體呈長圓形、胡蘿蔔狀或圓盤狀,在土中生長的部分均為無色或黃色到褐色,而暴露在地表的部分為綠色,也有真菌共生;木賊類的原葉體為墊狀,具直立的帶狀分枝,綠色自養;真蕨類的原葉體多為心形,綠色自養,也有的呈絲狀或帶狀.Fern gametophyte. Small, tend to live a shorter period, no roots, stems, leaf differentiation, only a rhizoid. Device on which to produce sperm and the archegonium, where fertilization of water under the conditions to complete the process. When fertilization eggs develop into the embryo splitting, young sporophyte grow after the prothallus gradually withering away. different species of fern leaves its original body shape, size and nutritional ways are different. If the original pine needles fern leaf lanes are irregular cylindrical , in the earth, no chloroplast, in vivo with vascular tissue, with their symbiotic fungi; Song-class of the original leaf lanes are long round, carrot-shaped or disc-shaped, part of the growth in the soil are colorless or yellow to brown , while the exposed parts of the surface is green, there are symbiotic fungi; Equisetum class prothallus of cushion-like, with upright branches of the ribbon, green self-supporting; true prothallus of ferns are mostly heart-shaped, green self-supporting, while others showed filamentous or ribbon.

詞條圖冊

原葉體原葉體

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