. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. 44 Science of Plant Life leaflets of the compound leaf droop downward from the peti- ole ; in the medium Hght of a cloudy day they are held per- pendicular to the Hght; in the most intense sunHght the blades are raised above the petiole until they are edgewise and point toward the light. Some observa- tion of bean seedlings, which may readily be grown in the laboratory, will be in- structive in this connection. Other examples of motile leaves may be seen in the honey locust, the lea
. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. 44 Science of Plant Life leaflets of the compound leaf droop downward from the peti- ole ; in the medium Hght of a cloudy day they are held per- pendicular to the Hght; in the most intense sunHght the blades are raised above the petiole until they are edgewise and point toward the light. Some observa- tion of bean seedlings, which may readily be grown in the laboratory, will be in- structive in this connection. Other examples of motile leaves may be seen in the honey locust, the leaflets of which fold upward at night, and in white clover, oxaHs, and the red-bud tree. The leaflets of the sensitive plant vary their positions according to Hght intensity, and also when touched or injured in any way (Fig. 3i). The change of position in motile leaves is brought about by changes iri the water content of the cells on oppo- site sides of a special organ called the pulvinus (Fig. 32), which is located at the base of the leaflets. This device may readily be studied in the leaf of the bean. The leayes of shade plants. As may be observed by a trip. Fig. 31. Sensitive plant. The leaves on the left side are in normal positions; those on the right side have been touched and the leaflets have folded together wholly or in part and the petioles have folded toward the stem. P is the 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 Transeau, Edgar Nelson, 1875-1960. Yonkers-on-Hudson, N. Y. , World Book Co.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1921
