摘要
对山药地上珠芽的发生规律进行解剖学系统观察。结果表明:山药珠芽发生于主茎或侧枝顶端向下第三节位的叶腋处。由叶腋表皮下1～2层细胞进行平周分裂,增加细胞层数,随后第二、三层细胞进行平周和垂周分裂,形成一团分生组织的珠芽原基。在外观上呈现嫩绿色球形小珠芽时,内部已分化出顶芽及多处根原基。顶芽和根原基的基部均有壳状区,形成与内部结构的分界,并对芽和根向外方生长有着一定的影响。幼嫩珠芽的结构,最外为一层表皮,表皮以内的数层薄壁细胞排列较为紧密,其内方有三、四层分生组织组成的分生带,珠芽中部的薄壁细胞富含淀粉及蛋白质颗粒,外韧有限维管束散生于薄壁细胞之间。成熟珠芽与之相比,最外为木栓质表皮,其内方为木栓形成层形成的周皮。由于分生带的作用,中部薄壁细胞数量增多,并伴随着细胞的增大,形成了成熟珠芽的一定形态和体积。
This article carried out an observation on the anatomical system to the generative law of the bulbil on the aerial part of the Chinese yam(Dioscorea batatas Dcne.).The result showed that the bulbil of the Chinese yam generated on the leaf axil of the top of the main stem or lateral branch downward to the third knot.From the 1～2 layer of the infracutaneous under the leaf axil,the cells carried out the pericli- nal division to increase the cell layer.Then,the cells on the 2nd and 3rd layer carried out the periclinal and antiolinal divisions to form a group of meristem bulbil primordium.When its appearance showed the milky white spherical bulbil,its iternal part differentiated the terminal bud and some root primordium.At the basic part of the terminal bud and root primordium,they all had a shell zone to form the dividing live with the internal structure to have the influence on the outward growth of bud and root.The structure of the young bulbil was as follows:Its most external part was a layer of epidermis.Several layers of parenchyma cells under the epidermis were arranged rather closely.In the internal part,3～4 layers of meristematic tissue cell formed the meristematic zone.The parenchyma cell in the middle part of bulbil was rich in starch and protein granules.The collateral closed vascular bundles were scattered among the parenchyma cells.Compared with the mature bulbil,the most outer part was phellogen epidermis and its internal part was the periderm formed by phellogen.Because of the action of meristematic zone,the internal parenchy- ma cell amount increased and then the cell enlarged to form certain shape and volume of the mature bulbil.
关键词
山药
珠芽
解剖结构
Chinese yam
bulbil
anatomical structure
