In order to analyse adaptive strategies in plants of Mediterranean annual grasslands in Sierra Morena (Spain) a group of morphological and functional characters have been measured in 43 common annual species of these grasslands. The principal component analysis of the species x characters matrix show that the main trend of variation is related with plant size. The smaller species show the smaller seeds, the higher growth rates, the higher reproductive effort and the shorter life cycles. The second trend of variation is related with shape, opposing plants with erect growth (grasses) to rosettes and prostrated ones. The evolution of these strategies in permanent plots measured along three years of increasing rainfall and with different grazing and fertilising treatments show that bigger species increase in cover with time in all plots, while smaller ones decrease. In plots with light or no grazing erect plants increase, while those with prostrate or rosette shape increase in high grazing ones.