Leaf anatomical characteristics of 4 Artemisia species under drought conditions were investigated to reveal the drought鄄resistant strategies of vegetation at early stage of ecological succession in the Loess Plateau. Three dominant species as Artemisia scoparia Waldst. et Kit., Artemisia giraldii Pamp. and Artemisia gmelinii Web. ex Stechm. and one common specie, Artemisia annua Linn. during early succession in the Loess Plateau were selected to investigate the leaf anatomical adaptation of Artemisia to soil drought stresses. Pot experiment was adopted to control the soil water content. And 75%, 55% and 35% of field moisture capacity were set as control, moderate water stress and severe water stress, respectively. The latest mature leaves were freshly collected and fixed at the end of their vegetation growth period for SEM, TEM and the optical microscope. We analyzed the difference among leaf epidermis characteristics of the four Artemisia species according to the sub鄄cellular micro characteristic and the organizational anatomical structure. The results show that: the four Artemisia http: / / www.ecologica.cn leaves have some kind of anatomy characteristics, as blade thickness, palisade tissue thickness, cutin layer thickness, ratio of palisade tissue thickness to sponge tissue thickness, tightness of leaf tissue structure were increased under drought conditions. Leaf epidermises of A. scoparia, A. giraldii and A. gmelinii have dense trichomes to prevent excessive water loss from evaporation; however A. annua has sparse trichomes. The upper epidermises of A. gmelinii and A. annua are sparse, which are not good for water conservation and to prevent highlight, the decrease of the stoma density and the number of chloroplast were conducted to adapt environment change. Similar chloroplast anatomy characteristics of thick grana and dense grana lamellae were observed in the leaf cells of A. scoparia and A. giraldii, which are easier to result in oxidative damage during photosynthetic process. To prevent the oxidative damage, the dense trichomes on upper epidermises of A. scoparia and outstanding antioxidant mechanisms of A. giraldii were conducted, and a large number of liposomes were also produced in the two species. The leaf anatomical characteristics influence of drought affected on the A. annua was the greatest between the four Artemisia species, and A. gmelinii and A. scopara were followed, the least affect was on Artemisia giraldii. The three dominant species had stronger ability to adapt to drought stress than the common species鄄Artemisia annua. The leaf anatomical characteristics and drought tolerance indexes of the 4 species represented similar comments of drought tolerance ability.

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