Abstract: In order to reveal the adaptive mechanism of the alpine plantMeconopsis integrifolia, we compared foliar structure ofM. integrifolia in Mount Balang along an elevation gradient (3681, 3841, 4081, 4215, 4452 m)， using paraffin wax slices method and microimaging technique. We found that there existed differences in foliar traits along the altitudinal gradient. With the increase of altitudes, the patterns of foliar traits were as follows: (1) plant height and basal diameter decreased; (2) leaf length and width decreased, while length width ratio increased; (3) palisade mesophyll thickness, palisade-sponge mesophyll thickness ratio and leaf cell tense ratio showed an increase, while the thickness of leaf, epidermis, sponge mesophyll, the midrib diameter, sponge ratio decreased; (4) leaf trichome density, stomatal density as well as stomatal index showed a trend of increase. Besides, we analyzed the correlation between the anatomical characteristics of leaves, and investigated the response and ecological adaptability of plant characteristics to different altitudes. The results indicated the occurrence of a significant co-evolution between anatomical indexes in leaves. In particular, indexes such as plant height and leaf size exhibited high plastic responses to altitudes. All these suggested that differences in either morphological or anatomical structure ofM. integrifolia along the altitudinal gradient might result from its adaptation to complex alpine environment.

Key words: rice, risk comparison., drought, Sichuan Basin