BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VIII. BASICS OF PLANT MORPHOLOGY AND ANATOMY

Root Morphology and Anatomy

Apical Meristem

This zone ensures Cell Division of the ROOT and its elongation. It consists of parenchymal Cells surrounded by a thin primary Cell wall, featuring dense Cytoplasm and a large nucleus. Cells in this zone actively divide, and therefore they are small and practically devoid of vacuoles. The apical meristem occupies the root tip, right beneath the root cap, and is only 2-3 mm long. Its characteristic feature is continuous cell division. The Structure of the root apical meristem is best described by Hanstein's histogen theory. According to this theory, three distinct zones, or histogens (precursors of future Tissues), can be distinguished in the root apex. The outermost uniform layer is called the dermatogen. It subsequently gives rise to the primary protective tissue of the root, the epiblema. Beneath it lie 4-6 layers of Cells of the periblema, which forms the primary cortex. The central part is occupied by the pleroma. This histogen gives rise to the procambium and the central cylinder.