Fig. 2From: Artemisia dominant species succession relating to the soil moisture decrease in abandoned land of the Loess Plateau (China): comparative study of drought-adaptive characteristicsStomatal density (a) and stomatal index (b) of the four Artemisia species. Upper leaf epidermis of A. annua is without stomatal distribution. Different letters indicate significant differences at P < 0.05. Values are presented as the mean ± SD, N = 6Back to article page