. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. by coiling, the body of the plant is drawn upward proportionally. It will be observed that the helix is interrupted at one or more points, above and below which the coils turn in opposite direc- tions. This is because the ten- dril is attached at both ends and cannot adjust itself to the oppo- site strains of torsion. Twist with your fingers a piece of tape so attached, and you will see that on one side of your hand it turns from right to left and on the other from left to
. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. by coiling, the body of the plant is drawn upward proportionally. It will be observed that the helix is interrupted at one or more points, above and below which the coils turn in opposite direc- tions. This is because the ten- dril is attached at both ends and cannot adjust itself to the oppo- site strains of torsion. Twist with your fingers a piece of tape so attached, and you will see that on one side of your hand it turns from right to left and on the other from left to right. 98. The cause of twining.— showing upper leaflets reduced to Botanists are not fully agreed on this point. The explanation most generally accepted at present is that the twining of stems is due to the combined action of lateral and negative geotropism (51). The first causes one side to grow more rapidly than the other thus forming a succession of coils, while the second, by stimulating the upward growth of the axis, stretches it into a spiral, and in this way draws it more tightly round the support. For this reason twining stems do best on an upright support. In tendrils, the twining is thought to be due not to gravity, but to contact with a solid body, which, by inducing unequal de- velopment on opposite sides of the tendril, of a passion flower causes it to turn about an available object, transformed into The coiling of the free part of the twining tendrils. (After , r ° quay.) organ is in response to the stimulus trans-. 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 Andrews, Eliza Frances, b. 1840; Lloyd, Francis Ernest, 1868-1947. ed. New York, Cincinnati [etc. ] American book company
Size: 1046px × 2391px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorand, bookcentury1900, bookdecade1910, booksubjectbotany
