During the formation of the primary plant body specific regions of apical meristem produces

During the formation of primary plant body, the dermal tissues, ground tissues and vascular tissues are produced by Apical meristems present at root & shoot apices. Intercalary meristems present on either side of nodes and caused to the linear growth in grasses. Lateral meristems present at the periphery (lateral side) of stem.

So these meristems are recognized on the basis of position.