Later, if the plant becomes woody, new secondary tissues arise from a different region of mitosis, the lateral meristems.
Plants that live for a long time, and especially those dicots and gymnosperms, which become woody and survive from year to year, do so as a result of lateral meristems. These cylinders of intensive mitotic activity give rise to secondary growth: tissues laid down toward the center of the plant become the secondary xylem, and those laid down toward the outside of the plant become the secondary phloem.
Bark is not wood but results from the activities of two lateral meristems: the vascular cambium, which produces phloem toward the outside, and the phellogen or cork cambium, which produces the cork and inner parenchymatous layer called phelloderm.
Apical meristems of the shoot and root lead to primary growth, and lateral meristems of the cambium and phellogen lead to secondary growth.
According to this view, under high nutrient supply, lateral meristems receive an "overflow" of nutrients that, because of their abundance, cannot be disproportionately channelled to the shoot apex.
A plant with extremely strong apical dominance may thus perform poorly relative to a plant that maintains some development of lateral meristems under conditions of intense competition for light.