Ground meristem The central region of the apical meristem from which the ground tissues of pith, cortex, medullary rays, and mesophyll differentiate. In root meristem it is also called periblem.

• 基本分生组织：位于顶端分生组织的中部，髓、皮层、髓射线以及叶肉这些基本组织均是由基本分生组织分化而成。根部分生组织也称为皮层原。