Mary Jo DiLonardo has worked in print, online, and broadcast journalism for 25 years and covers nature, health, science, and animals. Young trees sometimes have smooth bark that's unbroken by ridges.

The center of a tree or shrub stem (from roots to trunk, branches, and twigs) is woody, composed of xylem cells that conduct water from the roots to the upper parts of the tree. That woody section is ...

DARIEN -- Most people walk past trees and plants every day without paying much attention to the biological diversity surrounding them. "A lot of people walk through, and all they see is a tree," said ...

Why do trees have bark? Julien, age 6, Melbourne. This is a great question, Julien. We are so familiar with bark on trees, that most of us just take it for granted. But bark is one of the most complex ...