Auxins

Auxins - a group of plant hormones, synthesized in apical bud, baby leaves or seeds. They posses several functions: 

• stimulation of extension growth of plant cells, what enable the response of plant organs to directional stimulus 
• stimulation of cell division resulting in increase in the thickness of the stems and roots of plants
• resposible for the apical dominance
• stimulation of callus formation 
• inhibition of shedding the leaves and fruits