The vascular cambium forms phloem tissue outside and xylem tissue inside. The food is synthesized in leaves by photosynthesis. This synthesized food is moved to different part of the plant through phloem. On removal of tissue outside vascular cambium the food cannot be translocated and therefore, root become starved. The xylem present inner to vascular cambium and therefore, water moves up from root to leaves. The shoot becomes starved only after the root because the shoot can obtain food matter from leaves. Annual rings are formed due to secondary growth. The secondary growth is due to activity of vascular cambium. Since vascular cambium is present, therefore the annual rings are formed.