What is Ground Meristem in primary growing shoot?

The ground meristem produces new cells which ultimately develop into parenchyma cells. The central portion of the primary shoot within the ring of vascular strands is composed of ground meristematic tissues that later develop into pith, and the ground tissue outside the vascular cylinder will mature into the cortex. During the primary stage of growth, the cell layers of parenchyma ground tissue nearest the surface of the stem will develop chloroplasts and become green and photosynthetic.