why new stem can be grown from axillary bud only?
As we know in plants, meristems are present which are dividing cells. As leaves are formed by apical meristems,a small amount of dividing cells are left behind at the junction of stem and leaf which you called as axillary bud. These buds are cabable of division and may develop into stem or flower depending upon the harmone of plants. (activated or inhibited condition).