四种龙胆的显微结构特征比较

Comparisons on Microscopic Characteristics of Four Gentiana Species

为比较红花龙胆(Gentiana rhodantha)与翼萼龙胆(Gentiana pterocalyx)、滇龙胆(Gentiana rigescens)与头花龙胆(Gentiana cephalantha)的显微结构差异,用石蜡组织切片法及徒手切片法对4种龙胆的显微结构进行了研究。结果表明,红花龙胆与翼萼龙胆、滇龙胆与头花龙胆显微结构特征有明显区别。在根横切面方面,红花龙胆皮层厚,导管细胞横切口径小,无明显射线,翼萼龙胆的特征与红花龙胆的相反;滇龙胆与头花龙胆的表皮和皮层早脱,次生韧皮部发达,但滇龙胆韧皮部薄壁组织细胞较大,而头花龙胆较小。在茎横切面方面,红花龙胆中央髓约占切面的1/3,而翼萼龙胆约占切面的1/2;滇龙胆髓仅外部有散落分布的纤维束,头花龙胆髓部均可见纤维束散落分布。在叶横切面方面,红花龙胆中脉维管束较大,而翼萼龙胆较小;滇龙胆中脉维管束小,未见纤维束,头花龙胆中脉维管束大,纤维束成对位于木质部两侧。在叶表皮方面,4种植物表皮细胞径向壁波曲度与气孔指数有一定差异。根据显微结构特征可以将这4种植物区别开来。

Paraffin tissue sections were applied to compare the microscopic characteristics among 4 Gentiana species,including Gentiana rhodantha,Gentiana pterocalyx, Gentiana rigescens and Gentiana cephalanth~ The results of transverse sections from roots showed that, G. rhodantha were characterized mainly by thicker cortex, smaller vessel cells and inconspicuous xylem ray than G. pterocalyx. G. rigescens and G. cephalantha were both characterized mainly by early defoliation of cuticle and devel- oped phloem, however,G, rigescens had bigger parenchymal ceils than G. cephalantha. The results of transverse sections from stems showed that,the central medulla occupied 1/3 area of the transverse section from G. rhodantha and 1/3 area from G. pterocalyx,respeetively. The fibre bundles were found in the whole medulla of C. cepha!antha but only in the out layer of G. rigescens. The results of transverse sections from leaves showed that, G. rhodantha ascular bundles were bigger than ones of G. pterocalyx. Compared to the G. rigescens small ascular bundles without fibre bundles, G. cephalantha had bigger ascular bundles with paired fibre bundles being bilateral to the xylem. Additionally,the 4 Gentiana species have different epidermis cells in leaves with specific radial wall and stoma characteristics. The four species could be distinguished according to the microscopic characteristics.