Stele

Stele, the axial cylinder of tissue arising from one strand of plerome or axial generating-tissue, in which the vascular tissue originates. Most stems have one such cylinder, and are monostelic; but polystely, or the possession of several such cylinders, is frequent among Pteridopbyta (q.v.). The primitive stele may break up into several schizosteles, as in the stem of Equisetum, the Nymphaeaceae, etc., and in many leaves. The portion of the stele given off to a leaf is termed the meristele. The stelar tissue, whether united or schizostelic, is marked off from the extra-stelar ground-tissue by the endodermis. The stele may contain one or many vascular bundles.