Water diffuses into the plant when its osmotic pressure/water potential is lower than its surrounding soil. Water then enter the plant by two pathways: 1) diffusing through the epidermis, then the cells of the cortex, and enter the endodermis forced by the Casparian strip (or a band of suberin and lignin bordering four sides of root endodermal cells); 2) entering from root hairs, and diffuse through the cortex cells and the endodermis.

These two pathways lead to the vascular cylinder that contains xylem and phloem, which would be transporting water/minerals from the stem to the leaves. Xylem moves water and minerals from the roots to the. Within xylem, the tissues are tracheids and vessel elements. The tracheids form stronger walls than the vessel elements, but they form a less obvious means of transport with the pitted walls than the vessel elements. The vessel elements are larger than the tracheids; they have perforation plates separating one another. The hollow structure provides for most of the transportation. Water entering root cells creates a positive pressure called root pressure that primarily occurs at night. It tends to push xylem sap upward, creating guttation, or the forcing out of water out of vein endings along the edges of leaves.

Important mechanisms such as water's properties of cohesion/adhesion and transpiration are crucial to the rising of water to the tops of trees. Cohesion is the tendency of water molecules to cling together because of the hydrogen bonding. It keeps the water column in xylem from the leaves to the roots continuous and not easily broken. Adhesion is the great ability of water to interact with the molecules making up the walls of the vessels in xylem. This gives the water column strength from slipping back. When the water reaches the leaves, most of it would be released into the atmosphere by transpiration, or the process of evaporating water as the stomata opens up. Stomata open up by turgor pressure: the increase in turgor pressure tightens the guard cells, which lead to the opening of the stomata. When the turgor pressure decreases, the stomata would close. Transpiration is responsible for at least 90% of the water taken up by the roots. The opening of stomata and entering of carbon dioxide often leaves the mesophyll cells dry and exposed to the air, thus creating a tension that moves the water column passively upward.