guyThere is no homophone for the word community
It is because of the surface tension and cohesian of the molecules. It can be concave or convex.
This is a "pulling theory." Water vapor is released out of the leaf's stomata . Water behind it replaces the water lost. Water molecules "stick together" by cohesive forces (cohesian tension) , thus a column of water rises up the xylem tissue of the stem.The movement of sap (primarily downward) is an entirely different mechanism.