西洋参根的发育解剖学研究

西洋主根顶端的原分生组织由三群原始细胞组成。初生木质部为三原型。维管形成层产生的次生维管组织中薄壁细胞占主导地位；维管分子量少、聚集成群，分散在薄壁组织中。周皮加、周皮发生较迟，其木栓形成层由紧靠内皮层的皮层细胞产生。不同年龄西洋参主根随着龄龄的增加，周皮、次生真心皮部和木质部面积均呈增加趋势，但韧皮部与木质部面积比值自５：１下降至１：１。一年生根由中柱鞘产生初生分泌道，由维管形成层产生一圈次生分

DEVELOPMENTAL AND ANATOMICAL STUDIES ON THE ROOT OF PANAX QUINQUEFOLIUML.

The apical promeristem of main root of Panax quinque folium L.consists of three groups ofinitials.Primary xylem is triarch.Secondary vascular tissue,which originated from vascular cam-bium,contains mainly parenchyma in which a few gathered vascular elements dispersed.The for-mation of periderm is relatively late and cork cambium is come from the cortex cells which arenear endodermis.With age adding,the areas of periderm,secondary phloem and secondary xylemincrease,whereas the area ratio of phloem and xylem decrease from 5:1 to 1:1.One-year-oldquinqtiefolium produces one ring primary secretory canals from pericycle and one ring secondarysecretory canals from cambium.Afterwards,one ring secondary secretory canals increase with ageadding.However,the increasing becomes slowly from four-year-old quinquefolium.The abundantstarch grains are stored in parenchyma cells,and the PAS reaction shows that the amount ofstarch changes regularly at the different age.