Ce manuel introduit la biologie végétale, en se concentrant sur les faisceaux vasculaires trouvés dans les plantes comme le céleri et la banane. Il sert de base aux études agricoles et botaniques, offrant une compréhension de base de la structure et de la fonction des plantes.
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. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 82 THE PLANT: A GENERAL INTERNAL VIEW These groups or bundles of xylem and phloem are called the vascular bundles. You have frequently noticed vascu- lar bundles even though you did not recognize them by that name. When you eat celery which is a little too old to be tender, it is the stringy vascular bundles of it which get in your teeth. When you peel a banana you are sure to see vascular bundles. They either come off with the skin or stick to the pulp. If they stick to the pulp you strip them off, for they are too tough to eat. Many stems, however, are not dis- tinctly hard in the outer part and soft in the inner part like the stems we have been describing. In some stems you find no pith. Woody stems, like the stems of trees and shrubs, are hard all through. Such stems last over winter and form new layers of cuiar bundles are quite wood year by year. They do have distinct in this stem, ten of 1 i_ _n 1 • i_ j them being shown. Com- vascular bundles which are arranged pare with Figure 24 in in a cylinder, but the arrangement is which the bundles he made complex by the addition of new closely side by side. The L J tissue lying within the layers year by year. The arrange- ring of the bundles is pith. ment of woody stems is discussed in (So also in Figure 24.) the chapter devoted to stems. The stem of corn has still another arrangement. In it the hard parts, the vascular bundles, are scattered through the body of the stem. (See Figure 32.) They look in the picture like islands lying in the sea of softer tissue. Stems having this arrangement are common, but they. Fig. 31. — Half of a cross section of the stem of a common plant. The vas-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly r
