. Cyclopedia of American horticulture : comprising suggestions for cultivation of horticultural plants, descriptions of the species of fruits, vegetables, flowers, and ornamental plants sold in the United States and Canada, together with geographical and biographical sketches. Gardening; Horticulture; Horticulture; Horticulture. 1788 Youneseedhngshowme bendine towards the lieht be \\ell observed outside when the sun is low, and at any time of day with a window garden. An interesting case of the response to light is to be found in the wild lettuce {Lactuca Scariola), which is known as a com- pa
. Cyclopedia of American horticulture : comprising suggestions for cultivation of horticultural plants, descriptions of the species of fruits, vegetables, flowers, and ornamental plants sold in the United States and Canada, together with geographical and biographical sketches. Gardening; Horticulture; Horticulture; Horticulture. 1788 Youneseedhngshowme bendine towards the lieht be \\ell observed outside when the sun is low, and at any time of day with a window garden. An interesting case of the response to light is to be found in the wild lettuce {Lactuca Scariola), which is known as a com- pass plant. In sunlight this plant holds its leaves in a vertical plane, one row of leaves pointing north and the other south. This provision may be to avoid the full rays of the midday sun, and yet to secure the best ad- vantage of the less intense forenoon and afternoon sun- shine. The response of plant organs to the stimulus of light is known as heliotropism. In the same way plant organs will be stimulated to grow towards or away from air (aerotropism), a certain degree of moisture (hydrotropism), a definite tempera- ture (thermotropism), nutrient substances or other chemical agents (chemotropism) mechanical irritation (thigmotropism) and other stimuli. In all of these ways the plant is active and irritable. In all cases it is the active protoplasm which is concerned in determining the nature of the response. Temperature has a marked effect upon all living pro- cesses and it deserves particular mention. It may limit either by too great heat or too intense cold each of the particular vital activities. There are three critical tem- peratures for growth, a maximum or higher tempera- ture, a minimum or lower temperature beyond which on either side no growth takes place, and the optimum, or that intermediate grade which brings to the best devel- opment all of the faculties of the plant. Sometimes the optimum as reckoned by the amount of growth would not correspond to the optimum fo
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Keywords: ., bookcentury1900, bookdecade1900, booksubjec, booksubjectgardening
