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莼菜(Brasenia schreberi Gmel.)冬芽的形态结构及发育

THE MORPHORLOGY, STRUCTURE AND DEVELOPMENT OF WINTER BUD IN BRASENIA SCHREBERI GMEL.

  • 摘要: 本文报道了研究莼菜冬芽的结果。冬芽由肥大的茎、叶柄和缩小的叶片组成,整个器官外为粘液层所包围。叶肉组织排列紧密,无延伸开来的细胞空腔。缺乏气孔,只有一层发育微弱的栅栏细胞层。紧密的组织及许多质体中都载负有淀粉粒,说明其适应贮藏。叶柄的维管组织表现出特有的双韧维管束。中间的单管腔代表着木质部。茎的中央部分为一对双韧维管束所占据。冬芽由于离层而从母体脱落,在不低于4℃时能顺利越冬,翌春可萌发成新株,故可作为繁殖体。

     

    Abstract: The paper describes the results of a study of winter bud in Brasenia schreberi Gmel. The winter bud consists of a thickened stem, dwarf leaves with thickened petioles, and the whole organ is enveloped in the gelatinous layer.The blade of the leaf has a more compact mesophyll, lacking extensive intercellular spaces, it entirely lacks the stomata, and it has only one poorly developed palisade cell layer. The compact tissues and the abundant plastids are adapted to store starch.The vascular tissues of petiole show the characteristic double phloem and single canal representing xylem. The central portion of the stem is occupied by a pair of double phloem vascular bundles. The winter bud as an absiss-layer is detached from the parent plant, and falls to the bottom of the pond where it spend the winter, These winter buds serve as a vegetative organ. The winter buds would be killed by temperature below about 4℃,

     

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