Abstract: Comparative anatomy of leaf blade-midribs in the genera Thiadiantha, Baijiana and Momordica is made in this research. Except one species of Momordica, the anatomical da-ta often species are first reported here. The conclusions are: 1. The numbers of vascular bun-dles of leaf blade-midribs in Thiadiantha ranged from 2 to 5, arranged in lined, crossed, or horseshoe-like; in Baijiana from 6 to 7, and in horseshoe-like; and in Momordica from (1) 3 to 5, in horseshoe-like or T-formed. 2. The numbers and forms of arrangment of vascular bun-dles show a wide range of interspecific variation (rarely intraspecific). So those are very impor-tant from the taxonomic point of view. 3.The reduction of the number of vascular bundles is considered as an advanced character because those are assumed from the dry and hot district to a wet and cool one in habitat in evolution.

Key words: Thladiantha

摘要： 本文对赤属(Thladiantha Bunge)、白兼果属(Baijiana A.M．Lu et J．Q.Li)和苦瓜属(Momordica L．)共11种植物叶片中脉进行了比较解剖学研究。除苦瓜属一种外，其余10种的叶片中脉解剖学资料均为首次报道。分析结果表明：叶片中脉维管束的数目以及排列方式具有分类学意义，而种间和种内维管束数目的减少，在一定程度上反映出植物迁移和演化的方向。

关键词: 赤属, 白兼果属, 苦瓜属, 叶片中脉, 解剖