It occurs (extensions and bendings of the nodes) mainly due to geotropism (negative), when plant lying horizontally tries again stand up to the vertical position (they manage it using the nodes, one of whose function is leveling deviations from the vertical growth - negative geotropism).
Ni Hupatikana (upanuzi na bendings ya nodes) Hasa kutokana na geotropism (hasi) Wakati mmea imelala chali anajaribu tena kusimama na nafasi wima (wao kusimamia kutumia nodes, moja ya kazi ni ya nani leveling deviations kutoka ukuaji wima - hasi geotropism).