Share this credible answer with others. Simply paste this code into your blog or Web page:
As the stem grows older the pith usually dries out, and in some it disintegrates and the stem becomes hollow. In trees the pith becomes much reduced as the woody tissue (xylem) grows.
|
Answer verified with
|
HighBeam gives you access to newspaper, magazine, and trade journal articles plus press releases, facts, information, and biographies from thousands of sources.