OCR Text |
Show BARK ON TREES NOT. WOOD It Is Composed of Three Layers of Tissues, Tis-sues, Each of Which Has Important Impor-tant Function. Bark on trees and , shrubs corresponds corre-sponds with skin on animals. But It has other uses which the skin hasn't. Bark Isn't wood, and It Isn't formed as wood Is formed. It covers the wood, and It Is generally an easy matter to separate the bark from the wood. Hemp and Jute and flax are all bark the outside covering of certain vegetable vege-table growths. Bark Is composed of three layers of tissues. . The Inside layer conducts food to the plant, and under n magnifying mag-nifying glass Is seen to be made up of tiny fibers.' Then there Is the "green zone," as It Is called, and this also Is fibrous, and helps feed the plant. The outside layer Is cork, and Is really dead. That Is, these cork cells develop devel-op and die Immediately, so one really sees only a dead tree when he looks at the bark. The cork of commerce Is the bark of a certain kind of tropical trop-ical tree, but the outer layer of bark of all trees Is technically known as cork, and the little cells going to make It up are called cork. |