. A text-book of botany for secondary schools. Botany. 42 A TEXT-BOOK OF BOTANY. Fig. 41.—A scarlet runner bean, showing leaf- bearing nodes, internodes, and axillary branches. Branches as well as leaves appear at the nodes; and there is usually a very definite relation between them, the branch appearing in the up- per ansilc between leaf and stem, called the axil of the leaf (Fig. 41). Most branches are thus axillary in position. The inter- nodes give length to the stem, separating the nodes from each other, and so display- ing the lea^-es more freely to the air and the sunlight. 23. Directio
. A text-book of botany for secondary schools. Botany. 42 A TEXT-BOOK OF BOTANY. Fig. 41.—A scarlet runner bean, showing leaf- bearing nodes, internodes, and axillary branches. Branches as well as leaves appear at the nodes; and there is usually a very definite relation between them, the branch appearing in the up- per ansilc between leaf and stem, called the axil of the leaf (Fig. 41). Most branches are thus axillary in position. The inter- nodes give length to the stem, separating the nodes from each other, and so display- ing the lea^-es more freely to the air and the sunlight. 23. Direction of steins.—The dire'ctions in which stems grow are due to a varietj' of causes, some of which will be considered later; but for the present only certain positions will, be noted. (1) Erect stems.—The upright stem is the most common; and it seems altogether the best adapted for the proper display of leaves, for they can be spread out on all sides and carried upward toward the light. To maintain the erect position is not a simple mechanical problem, and in large woody stems it invoh-cs an extensive development and arrangement of supporting tissues. That some special organization is necessarj' to maintain the erect position in the air is evident when aerial erect stems are contrasted with submerged erect stems. In small lakes and slow- moving streams submerged plants ai-e commonly seen, as the pickerel-weed and numerous others. In the water the stems are erect; but when taken out thej' collapse, having been sustained in position by the water. Among aerial stems the tree is the most impressive, and. 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 Coulter, John Merle, 1851-1928. New York, D. Appleton
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