中文摘要：

导管的大小、形态和彼此连接方式的不同对水分运输和应力支撑有重要作用。本研究采用树脂铸型法对毛白杨（Populus tomentosaCarr）、旱柳（Salix matsudana）、榆树（UlmuspumilaL．）和紫藤（Wisteria sinensis）4个树税的导管分子三维结构进行比较研究，分析导管结构特征和其水分输运的关系。导管内壁结构被印在铸型的表面上，将铸型放在扫描电子显微镜下观察。结果表明：旱柳和毛白杨的导管分子特征较接近，与榆树和紫藤存在明显差异，相对于榆树和紫藤较原始。毛白杨和旱柳的导管分子长、侧壁纹孔少，有利于水分的输运。榆树和紫藤的导管分子相对宽，穿孔板几乎平直，更加利于水分的输运。榆树和紫藤的细导管分子有螺纹加厚，可增加导管的机械强度，减少管内产生空穴化的风险，从而保证水分更有效的运输。

英文摘要：

The size, form and connection mode of vessel displayed an important role in water transportation and stress support of the plant. Based on resin casting method, the three - dimensional structure characteristics of the vessels of four plant species, i.e. Populus tomentosa Cart, Salix matsudana, Ulmus pumila L. and Wisteria sinensis were comparatively studied. The relationship between the vessel structure characteristics and water transportation was analyzed. The vessel wall structure was printed in molded surface, which can be examined with SEM. The results showed that： the structure characteristics of the vessel element of P. tomentosa Cart are similar to those of S. matsudana. However, they are significant different from U. pumila L. and W. sinensis, and more primitive than U. pumila L. and W. sinensis. The vessel elements of P. tomentosa Carr and S. matsudana are long, and the pits are less, which is beneficial to water transport. The vessel elements of U. pumila L. and W. sinensis are relatively wide and straight of the end wall, which are helpful for water transport. There is spiral thickening for U. pumila L. and W. sinensis, which increase the mechanical strength of vessel and decrease the risk of cavitations, consequently improve the efficiency of water transport.