tunica-corpus theory

A concept of the organization and development of the *apical meristem , in which the meristematic region is differentiated into an outer peripheral layer or layers, termed the tunica, and an inner mass of cells, termed the corpus. The tunica is characterized by chiefly anticlinal divisions and the corpus mainly by periclinal divisions. The corpus gives rise to the interior part of the plant body and the tunica differentiates the outer layers including the epidermis. Compare histogen theory.