Why do plants have pith and how is it useful to them?

Question

Many plants have pith, from walnut trees to corn to ragweed, but I can't think of anything it does them. What is pith and how is it useful to them?

Answer 1

The cells that make up "pith" are largely for mechanical support. In herbaceous plants these cells would be the ones in between the xylem and phloem. I would assume some plants also store starches and other materials. Varying the hydro static pressure in the cells on one side of a stem from the other is how plants orientate their leaves to track the Sun. I am fairly certain the cells that constitute the pith in plants like sunflowers near the head of the "flower. A sunflower consists of a lot of smaller flowers surrounded by a ring of modified leaves most call petals. Plants have relatively few cell types compared to animals. The long story short of "pith" cells is they are any interior cell that isn't directly related to the xylem and the phloem. In woody plants they are largely restricted to the newer growth and the leaves of the plant.