. Principles of modern biology. Biology. U3aNutrition of Multicellular Plants HOLOPHVTIC nutrition became dominant in the plant kingdom dining an early evolu- tionary period, and as multicellular species developed they gained greater efficiency by a division of labor among the cells. Thus gradually the specialized tissues and organs of the modern higher plants came into being. MULTICELLULAR ALGAE All early primitive plants lived under water, and the aquatic environment puts little premium upon the de\elopment of specialized parts. Natural bodies of water contain adequate amounts of carbon diox
. Principles of modern biology. Biology. U3aNutrition of Multicellular Plants HOLOPHVTIC nutrition became dominant in the plant kingdom dining an early evolu- tionary period, and as multicellular species developed they gained greater efficiency by a division of labor among the cells. Thus gradually the specialized tissues and organs of the modern higher plants came into being. MULTICELLULAR ALGAE All early primitive plants lived under water, and the aquatic environment puts little premium upon the de\elopment of specialized parts. Natural bodies of water contain adequate amounts of carbon dioxide, oxygen, and inorganic salts, so that every cell of a submerged plant can absorb these foods on an individual basis. Hence—as might be expected—the degree of differenti- ation among the cells of the green algae has not been very great. Perhaps the commonest type of cell dif- ferentiation among nonmotile green algae is the modification ol some of the cells to form organs of attachment. In some filamentous algae, a single cell at the basal end of the filament is specialized as a rhizoid (or hold- fast) that attaches the filament to the soil or rock at the bottom of the water (Fig. 13-1). This specialized cell is modified in shape and. Fig. 13 tiation. a pond 236 CHLOROPLAST 1. Young filament of Ulofhrix, a filamentous green alga, showing a slight degree of cellular differen- Normally this plant grows in a more or less vertical position attached to some object on the bottom of or 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 Marsland, Douglas, 1899-. New York, Holt, Rinehart and Winston
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