【摘要】 通过组织切片和显微观察等方法,对垂榆、黄榆以及家榆木质部中导管数量、分布、直径、长度的比较研究,发现三种榆木质部中导管分布密度、直径及射线密度由大到小依次为黄榆,垂榆,家榆.但导管分子端壁斜度由大到小依次为家榆,垂榆,黄榆.研究结果表明三种榆在进化上的关系为:黄榆最为进化,其次为垂榆,再次为家榆.更多还原

【Abstract】 By means of biological slice and microscope observation,I compare the sum,distribution,diameter,length in Xylem among Ulmus pumila var. pendula,Ulmus macrocarpa and Ulmus pumila was iniestigated. I found that the order the density of vessel distributions,the vessel diameter and the ray density in Xylem of the three,is Ulmus macrocarpa Hance,Ulmus pumila var. pendula Rehd,Ulmus pumila Linn. But the slant angle of the end wall in the vessel,the order from the big to the small is Ulmus pumila Linn,Ulmus pumila var. pendula Rehd,Ulmus macrocarpa Hance. The results show that the most evolutionary one among the three is Ulmus macrocarpa Hance,the second one is Ulmus pumila var. pendula Rehd and the last one is Ulmus pumila Linn.更多还原