. Botany for agricultural students . Botany. STRUCTURE OF MONOCOTYLEDONOUS STEMS 189 they do not collapse under the pressure of surrounding tissues, may form rings as in annular vessels, spirals as in spiral vessels, or be more generally distributed over the wall, leaving only small unthickened areas which constitute the pits characteristic. Fig. 167. — Cross section of a vascular bundle of Corn highly magnified. s, strengthening tissue; p, phloem consisting of sieve vessels (e) and companion cells (c); X, xylem consisting of annular vessel (a), spiral vessel (h) and pitted vessels (i); 6, par
. Botany for agricultural students . Botany. STRUCTURE OF MONOCOTYLEDONOUS STEMS 189 they do not collapse under the pressure of surrounding tissues, may form rings as in annular vessels, spirals as in spiral vessels, or be more generally distributed over the wall, leaving only small unthickened areas which constitute the pits characteristic. Fig. 167. — Cross section of a vascular bundle of Corn highly magnified. s, strengthening tissue; p, phloem consisting of sieve vessels (e) and companion cells (c); X, xylem consisting of annular vessel (a), spiral vessel (h) and pitted vessels (i); 6, parenchyma cells. of pitted vessels. The xylem vessels are free from protoplasm and are composed of cells joined in series with end walls resorbed. They are known as tracheae, and are quite tube-like in struc- ture and function. Through them the water and mineral salts from the roots are carried, some reaching the leaves and buds while much leaks out through the cellulose portions of the walls to supply the tissues of the stem. Around the vessels are the thin-walled parenchyma cells which may function some in con- In the phloem there are sieve vessels and companion cells. The sieve vessels are composed of cells joined in series and so named because of the perforated areas occurring in their end and side. 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 Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
