If a tree lives through a dry season, it remembers how hard it was to find water. The next time the dry season comes, the tree can react better. It might make its leaves smaller to lose less water or make them thicker to save more water. It might also grow its roots deeper to find underground water. The ⓐlong the dry season lasts, the ⓑdeep the roots may grow. In these ways, what trees remember helps them survive.