It is the action of van der Waals forces, which are reflected in the immediate vicinity of objects (containing a certain percentage of moisture), or their direct touching (leaves, stalks).
Ni hatua ya van der Waals vikosi, ambayo yalijitokeza katika maeneo ya karibu ya vitu (zenye Asilimia Baadhi ya unyevu), au kugusa yao moja kwa moja (majani, mabua).