贵州苏铁根的解剖学研究*

对贵州苏铁( Cycas guizhouensis K. M. Lan et R. F. Zou) 的根进行了解剖学研究, 结果表明: ( 1)
据外部形态和内部结构不同, 贵州苏铁的根可分为正常根、珊瑚状根和肉质根三种类型。( 2) 正常根与肉
质根的木栓形成层起源于表皮内方第1~ 2 层皮层薄壁细胞, 珊瑚状根的木栓形成层则起源于外方皮层的
第2~ 3 层细胞, 而非中柱鞘。( 3) 首次发现肉质根一种新的增粗方式, 是由周皮内方的皮层薄壁细胞恢
复分裂能力, 持续或周期性产生新的皮层薄壁细胞, 引起根的增粗。

Study on Anatomy of the Root of Cycas guizhouensis ( Cycadaceae)

The root anatomy of Cycas guizhouensis has been investigated. The result demonstrated that the roots may be
divided into three types, normal, coralline and fleshy ones, according to their morphology and anatomy. The phellogen
of normal and fleshy roots were derived from the first and second parenchyma cel-l layers of epidermis inside, whereas that
of coralline root came from the second and third cortical layer cells below epidermis.