What is the soft, spongy material found in the center of certain plant stems called?

The soft, spongy material found in the center of certain plant stems is known as pith. Pith serves several important functions in plants. Mainly, it acts as a storage area for nutrients and water, and it provides structural support to the stem. The cellular structure of pith allows for a substantial amount of space, making it effective for the storage of substances that the plant needs for growth and survival.

In the context of plant anatomy, phloem is responsible for transporting sugars and nutrients produced during photosynthesis from the leaves to other parts of the plant, while xylem transports water and minerals from the roots to the leaves. The cortex, located between the epidermis and the vascular tissues, often functions in storage and transport but is not central like pith. Each of these components plays a unique role in plant health, but in this case, pith is specifically characterized as the central, soft, spongy material of the stem.