梓树幼苗初生维管系统的解剖学研究

Anatomical Study on the Primary Vascular System of Seedling of Catalpa ovata

根据子叶节区理论对梓树幼苗初生维管系统进行了解剖学研究。结果表明:梓树幼苗的子叶节区较长,自上到下都有髓的存在,为向基移位型。子叶节区下部具有中始式四原型管状中柱,在子叶节区中部的原生木质部处一分为二,逐渐形成具有8枚外韧维管束的中柱结构;在子叶节区上部,组成短轴的2枚维管束各自一分为三,逐渐形成真中柱的雏形,与上胚轴顶端分生性组织分化形成的内始式真中柱相连,至此,子叶节区发育完成。子叶为单隙三迹。

Based on the cotyledon node zone（CNZ） theory,the anatomical study on primary vascular system at seedling stage of Catalpa ovata.The results indicate that the CNZ of C.ovata is longer,and belongs to basipetal shifting type.From top to bottem,it has pith in the whole CNZ.There is mesarch tetrarch siphonostele in the lower portion of the CNZ,which divides into two parts from protoxylem in the middle portion of the CNZ and gradually form stele structure with eight collateral bundles.In the upper portion of the CNZ,two vascular bundles which formed shorter axile divide into three parts respectively and shape the model of eustele,then connect with endarch eustele of epicotyl.There are three-trace cotyledonary node in the seedling.