Tree water transport. Artwork illustrating the movement of water through a tree (blue arrows). Water is taken up by the root hairs (bottom left) on the roots. It moves upwards through the tree, through the xylem tissue, the rigid woody tissue seen in the circle at lower left. Water is lost from the leaves by transpiration. This is the evaporation of water out of pores (stomata, top right) in the leaves. Trees can reduce their transpiration rate in dry air by closing their stomata. Mineral ions are transported in the water column, also called the transpiration stream.