甘草根和根状茎的发育解剖学研究

甘草（ＧｌｙｃｙｒｒｈｉｚａｕｒａｌｅｎｓｉｓＦｉｓｃｈ）实生苗具直根系。其根端原分生组织具三层原始细胞，外层产生表皮和根冠，中层和内层分别产生皮层和中柱。根的初生木质部四原型，由中柱鞘细胞产生第一次周皮。成长根中央的初生木质部由于导管周围薄壁细胞的增殖而被分割成几部分，使导管分子星散分布于薄壁细胞间。实生苗生长到第三年春由于叶节处的更新芽萌发形成最初的根状茎，根状茎顶端的原分生组织由两层原套细胞和一团原体细胞组成。初生结构的分化开始于皮层和髓两部分基本分生组织，而原形成层早期在根状茎横切面上呈连续的分生组织环。以后在环内逐渐分化出原形成层束，由它分化出初生锥管束，根状茎第一次周皮产生于初生韧皮部外方的第五或第六层皮层细胞。

DEVELOPMENTAL ANATOMY OF ROOT AND RHIZOME IN GLYCYRRHIZA URALENSIS

The seedings of Glycyrrhiza uralensis have tap-root system.Promeristem is composed ofthree layers of cells in root tip,of them,outer layer of cells form the epidermis and root cap,centraland inner layers of cells sepratedly form the cortex and vascular cylinder.The number of pro-toxylem of root is tetrarch,the periderm is firstly derived from the pericycly.The promary xylem ofthe growing root is found to divede into several parts and the vessel members scatteredly distributeamong the parenchymous cells,which is caused by preliferation of the parenchymous cells aroundthe vessel members.The earlist rhizome is formed from renewel buds at the cytolendonary node of the seedlinggrowing in the third spring,the promeristem consists of two layers of tunica cells and a group ofcorpus cells.The earlist primary structure firstly differantiates in the ground meristim to form thecortex and pith,at the early stage of rhizome development the procambium shows continue ring-likemeristem in the cross-section of rhizome ,then the procambium is gradually formed in the ring,andthe primary vascular bundle is formed from the promeristem. The earlist periderm is formed fromfifth or sixth layer of cortex cells outside phloem in the rhizome.