DENDROLOGY

Detailed explanation-1: -The continuous evaporation of water (or transpiration) from the cells of a leaf crates a kind of suction which pulls up water through the xylem vessles. Thus, transpiration helps in the upward movement of water and dissolved minerals from the roots to the leaves through the stem.

Detailed explanation-2: -The main force by which most of the water within xylem vessels moves toward the top of a tree is the evaporation of water through stoma. Evaporation from the mesophyll layer surface in leaves to their surroundings via stomata on the leaves causes transpirational pull.

Detailed explanation-3: -In order for water to move upward through the plant, diffusion, transpiration and capillary action must occur together. Water diffuses into the root creating pressure and pushing the water along the xylem. Transpiration causes water to leave the plant resulting in a force that draws water up through the xylem.