Water goes up through xylem vessels in tall trees. The process in plants and properties of water that help in upward movement are:

The upward movement of water in tall trees is primarily driven by the cohesion-tension theory. Transpiration, the evaporation of water from leaf surfaces, creates a negative pressure or 'transpiration pull' that sucks water upward through the xylem [1]. This process is supported by two critical physical properties of water: cohesion and adhesion. Cohesion refers to water molecules sticking to each other via hydrogen bonds, forming an unbroken, continuous column within the xylem [3]. Adhesion involves water molecules sticking to the cellulose walls of xylem vessels and tracheids, which helps stabilize the water column against the force of gravity [3]. While root pressure contributes to water movement, especially at night, it is insufficient for tall trees where transpiration pull is the dominant force during the day [1]. Respiration provides energy for growth but is not a direct mechanism for the physical ascent of sap [2].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.8 > p. 95
2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC5591614/
3. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 10: Life Processes in Plants > In a Nutshell > p. 150