. Nature-study; a manual for teachers and students. Nature study. LESSONS WITH PLANTS 305 to the light. Annual plants have soft or herbaceous stems. Perennial shrubs, vines, and trees have hard and woody stems. Compare them. Cut across a young, herbaceous stem hke a cornstalk and note the thread-hke strands that run through it. These may be shown better by cutting through the hard outer layer of the stalk and breaking and pulling apart the rest, when the strands will ap- pear as threads projecting out from the stalk. Tliese strands are found in all stems and are very important. They consist pa
. Nature-study; a manual for teachers and students. Nature study. LESSONS WITH PLANTS 305 to the light. Annual plants have soft or herbaceous stems. Perennial shrubs, vines, and trees have hard and woody stems. Compare them. Cut across a young, herbaceous stem hke a cornstalk and note the thread-hke strands that run through it. These may be shown better by cutting through the hard outer layer of the stalk and breaking and pulling apart the rest, when the strands will ap- pear as threads projecting out from the stalk. Tliese strands are found in all stems and are very important. They consist partly of strong cells that give rigidity and strength to the stem, and partly of duct-like or tubular cells that allow the sap to flow through them. These strands of strengthening and conducting tis- sues are called, technically, fibro- vascular bundles, and serve as a sort of skeleton for the plant and as its circulatory system. Some ducts convey sap up, while others let it down to the root. In plants that have two cotyledons or seed leaves in the seed, as for example, the pea, bean, sunflower, geranium, squash, box-elder, hlac, etc., the fibrovascular strands are arranged in a ring around a central pith. Cut across a young sunflower stem or young lilac shoot and this can be seen. Press the stem and see the water exude from cer- tain parts of the ring. Here are the tubular conducting. Fig. no Fibrovascubr Strands i Plantain 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 resemble the original Holtz, Frederick Leopold, 1870-. New York, C. Scribner's Sons
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