# The rupture and fractionation do not usually occur in the water column in vessel / tracheids during the ascent of sap because of :

$\begin {array} {1 1} (1)\;transpiration\: pull & \quad (2)\;lignified \: thick\: walls \\ (3)\;cohesion\: and \: adhesion & \quad (4)\;weak\: gravitational\: pull \end {array}$