远志根的发育解剖学研究

运用石蜡切片法对远志根的发育过程及1~3年生根的结构进行解剖学研究。结果显示:远志根的原分生组织由3群原始细胞组成,具有典型分生组织的细胞学特征。初生分生组织分化为根冠原、表皮原、皮层原和中柱原;初生结构由表皮、皮层和中柱组成,初生木质部为二原型。次生生长是依靠维管形成层和木栓形成层的活动完成,次生结构从外到内由周皮和次生维管组织组成;远志根次生结构特点为:次生韧皮部在次生维管组织中占主要部分,次生韧皮部中以韧皮薄壁细胞为主且其中储存有丰富的内含物,随着根龄的增加,韧皮薄壁细胞中的内含物也随之增加。3年生的主根中次生韧皮部薄壁细胞中的内含物最丰富;不同年份远志的主根随根龄的增加,周皮、次生韧皮部和次生木质部的面积都呈增加趋势,其中韧皮部和木质部的面积比值随根龄增长呈由小到大的变化,这是远志根的显著特点;根中的周皮发达,具有较厚的木栓层,次生木质部中导管和纤维发达,导管分布频率较高,并具有较大的口径。周皮和次生木质部的结构特征与远志的抗旱特性相适应。

Developmental and Anatomical Studies on the Root of Polygala tenuifolia Willd.

The root developmental process and root structure of one-year,two-year and three-year Polygala tenuifolia Willd.were studied with paraffin sectioning.It was shown that the apical promeristem consisted of three groups of initials,and they possessed the typical cell characteristics of meristem.The primary meristem consisted of calyptrogen,primordial epidermis,periblem and plerome;while the primary structure consisted of epidermis,cortex and central cylinder,and primary xylem was diarch.The progress of the secondary growth depended on the activity of vascular cambium and cork cambium.The secondary structure included periderm and secondary vascular tissue from the outer to the inner.There were three characteristics of secondary structure of P.tenuifolia:the secondary phloem had major part of secondary vascular tissue,among which the secondary phloem contained mainly parenchyma with abundant storage,and the storage became more and more with the age adding,thus the parenchyma of three-year root had the most storage;the areas of periderm,secondary phloem and secondary xylem increased with the root-year increasing,whereas the area ratio of phloem and xylem had a trend from lower to higher,which was the obvious feature of P.tenuifolia;P.tenuifolia had developed periderm which with thick cork,and secondary xylem contained mainly vessels and fibers.The vessels distributed frequently and had wide diameter.The structure features of cork and secondary xylem adapted to the xeromorphic characteristics of P.tenuiflia.