primary growth

This term is a specialized botanical descriptor used to distinguish longitudinal extension from lateral thickening. It refers specifically to the activity of apical meristems, which allow a plant to extend its reach upward toward light and downward into the soil for nutrients.

In a biological context, primary growth is contrasted with secondary growth, which involves the increase in girth or thickness of stems and roots. While primary growth occurs in all vascular plants, secondary growth is primarily characteristic of gymnosperms and woody dicots.