盾叶薯蓣根状茎的发育解剖学研究

Studies on the developmental anatomy of rhizome in Dioscorea zingiberensis

利用石蜡切片法对盾叶薯蓣根状茎进行了发育解剖学研究。盾叶薯蓣的二年生根状茎主要由三部分组成:周皮、基本组织和散生在基本组织中的维管束。周皮由木栓层、木栓形成层和栓内层组成;基本组织都由薄壁细胞组成;维管束无束中形成层,属于有限维管束,成熟的维管束由厚壁组织细胞形成的维管束鞘包围。根状茎顶端的原分生组织由3～5个鳞片包被。其衍生细胞分化为原表皮、基本分生组织和散生的原形成层束。以后由它们分化为表皮、基本组织和散生的维管束构成的初生结构,根状茎顶端下方的原表皮内存在初生增厚分生组织。初生增厚分生组织细胞不断向内分裂和其衍生细胞的体积增大,是根状茎能迅速增粗的主要原因。

Studies on the developmental anatomy of rhizome in Dioscorea zingiberensis C. H. Wright have been done with the paraffin method. The biennial rhizome of D. zingiberensis is composed of three parts: the periderm,the ground tissue and the vascular bundle. The periderm is the secondary protective tissue of the rhizome,and is composed of pellem,pellogen and phelloderm;the ground tissue is composed of parenchyma cells;mature vascular boundle, which belongs to closed vascular boundle with no intrafascicular cambium in it,is surrounded by vascular bundle sheath,which is composed of mechanical tissue cells whose cell wall is thickened. The primordial meristem at the tip of rhizome is surrounded by 3-5 lepises. The differentiation of the cells derived from the primordial meristem forms protoderm,ground meristem and adsperse procam-bium strand. After wards, the primary structure of the rhizome is formed after the formation of epidermis, ground tissue and adsperse vascular bundle differentiated from primary meristems respectively. There is primary thickening meristem at the lower part of rhizomatic tip under protoderm. The main reason of rapid thickening of the rhizome is that the increase in cells number derived from primary thickening meristem and in cells volume.