Abstract: In order to understand the heat resistance mechanism and the level of heat resistance of Dove tree(Davidia involucrata) populations in Sichuan Province, 16 anatomical structures of 15 representative natural populations in Sichuan Province were investigated by paraffin section and NaClO. Moreover, coefficient of variation, correlation analysis, and cluster analysis were used to screen representative structures. The 16 anatomical structure indexes all reached a significant level difference among 15 natural populations(P<0.01), thickness ratio of palisade and spongy tissue, thickness of palisade tissue, stoma density, cuticle thickness of lower epidermis, protuberant degree of main vein, cuticle thickness of upper epidermis, cuticle thickness of upper epidermis and thickness of lower epidermis were the main factors related to the heat resistance, while other indexes, such as leaf thickness, sponge tissue thickness, thickness of main vein, thickness of epidemic cell, thickness of vascular bundle in main vein stoma length, stoma width, tightness of leaf structure and looseness of leaf structures did not show much effect on heat resistance. There were some differences among 15 populations in heat resistance, and the descending order was Hanyuan, Junlian, Leibo, Muchuan, Pingshan, Yingjing, Tianquan, Meigu, Pingwu, Bifengxia, Beichuan, Hongya, Baoxing, Dayi, Qionglai. According to the heat hardiness, these populations could be divided into four groups, Hanyuan; Jun Lian, Leibo and Muchuan; Pingshan, Yingjing, Tianquan, Meigu, Pingwu, Bifengxia, Beichuan LR; and Hongya, Baoxing, Dayi, Qionglai.

Key words: Davidia involucrata, natural populations, heat resistance, anatomic structures