. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. 40 Science of Plant Life approximately at right angles to the Hne along which the greatest amount of light reaches them. Consequently the leaves on most of our common trees, shrubs, and herbs tend to take an approximately horizontal position. The sugar maple and the horse-chestnut are examples of trees whose leaves are displayed in this manner. In the cottonwood and tulip tree the leaves are only sHghtly sensitive to light, and the result is that their leaves assume a great variety
. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. 40 Science of Plant Life approximately at right angles to the Hne along which the greatest amount of light reaches them. Consequently the leaves on most of our common trees, shrubs, and herbs tend to take an approximately horizontal position. The sugar maple and the horse-chestnut are examples of trees whose leaves are displayed in this manner. In the cottonwood and tulip tree the leaves are only sHghtly sensitive to light, and the result is that their leaves assume a great variety of positions. If leaves are extremely sensi- tive to light, the blades may turn toward the sun in the early morning and follow the sun throughout the day, always keeping the broad face of the leaf to the light. The leaves of the common mallow move in this way. Compass plants. There is another class of plants which are sensitive to light, but which respond to it in a very different manner. These are the so-called compass plants, of which the wild prickly let- tuce is a widely distributed example. In sunny situations the leaves of these plants tend to take positions edgewise to Fig. 27. Pricklylettuceplant: 4, viewed the direction of the mOSt in- from west; 5, viewed from south. Drawn ±. „„ r 1,4. a ii ^• 1 1 from a specimen grown under exposure \^'^^^ ^^g^t. As the SUnhght to bright sunlight. is most intense at noon, it is. 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
