菠菜根异常次生结构的发育解剖观察

STUDIES ON THE DEVELOPMENTAL ANATOMY OF ANOMALOUS SECONDARY STRUCTURE IN ROOT OF SPINACIA OLERACEA L.

在菠菜的成长根内,正常维管柱的周围具有3或4轮呈同心环状排列的异常维管束,被薄壁或厚壁结合组织分开。在根的发育过程中,初生生长和早期的次生生长都是正常的。但是,后来在正常维管柱的外围以离心的顺序先后发生3或4轮异常形成层。第一轮异常形成层起源于中柱鞘向内衍生的细胞。后一轮异常形成层是在前一轮异常形成层最先向外产生的薄壁组织中发生。各轮异常形成层都以正常的方式活动,产生同心环状排列的异常维管束以及它们之间的结合组织。

The development of anomalous secondary structure in root of S pinacia oleracesa L. was investigated. The primary and initial secondary structures in the root are similar to those of most of herbaceous dicotyledons. But then 3 or 4 rings of anomalous cambia occur centrifugally. The first anomalous cambium arises from the derivative cells of pericycle, while the successive ones in layer of parenchyma cells derive from the current cambium. Each ring of cambia differentiates xylem inside and phloem outside in composing one ring of anomalous vascular bundles which are separated by parenchyma or sclerenchyma conjunctive tissues.