药用植物川牛膝根中异常次生结构的发育解剖学研究
ANOMALOUS SECONDARY THICKENING IN THE ROOTS OF MEDICINAL SPECIES OF CYATHULA OFFICINALIS KUAN.
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摘要: 药用植物川牛膝的根内具有异常的次生结构。其异常的次生生长是由维管柱外围发生的异常形成层通过正常的活动方式完成的。后一轮异常形成层起源于前一轮异常形成层向外产生的薄壁组织细胞,位于韧皮部的外侧。每一轮异常形成层向内产生木质部,向外产生韧皮部,组成异常维管束。其中,木质部最先开始分化。异常维管束排成螺旋状,分散在结合组织中。除最外轮一些木质部束之间的结合组织是厚壁组织外,其余结合组织都是薄壁的。由于初生结构和早期的次生结构是正常的,所以,这种异常结构可能是后起的特征。Abstract: Cyathula officinalis Kuan., a medicinal plant, is one of the species of Amarantaceae which shows anomalous secondary thickening in its root. The anomalous secondary thickening is by means of a succession of bidirectional cambia. The succeeding cambia initial periodically by periclinal division in a layer of parenchyma cells adjacent to the outmost elements of the phloem derived from the current cambium, each giving rise on its inner side to the xylem of the bundles, on its outer side to the bast. The former appears earlier than the latter. The anomalous vascular bundles are put in spiral order scattered in conjuctive tissues which are parenchyma except those that are sclerenchyma between some xylem strands of the outmost ring. The anomalous secondary structure of this kind may therefore be reconstructed as the primary and early secondary structures are normal.