Shelter-tents in the form of propagating-houses could be used advantageously in those sections in which the winters are mild, but where some form of shed is essential.
Small frames covered with cloth for coldframe purposes should be painted with raw linseed oil if imperviousness and durability are desired.
Miscellaneous screens.— In some regions, mat tings may be cheaply prepared from plant products. In the far South palmetto leaves have been used successfully, and straws of various kinds have been employed in countries where labor is cheap. In the Riviera section of France and Italy a very common species of heath, Erica arborea, is valuable for this purpose. Its uniform height after a few years of growth, the slender yet dense branches, and its lightness, render it very efficient and remarkably cheap. Bamboo has been employed where it is sufficiently common.
Literature.
General references: The Pineapple Industry in the United States, Yearbook United States Depart ment of Agriculture, 1895, p. 274 ; American Gin seng, Bulletin No. 16 (revised edition), Division of Botany, United States Department of Agriculture, 1898 ; Growing Sumatra Tobacco under Shade, Bulletin No. 20, Bureau of Soils, United States
Department of Agriculture, 1902 ; Growing Straw berries Under Cover, The Strawberry Specialist, February, 1902; Experiments in Ginseng Culture, Bulletin No. 62, Pennsylvania Agricultural Experi ment Station, 1903; Shading, Proceedings of the Society for Horticultural Science, 1903 (several papers); An Experiment in Shading Strawberries, Bulletin No. 246, New York (Geneva) Agricultural Experiment Station, 1904 ; Tent-Covering for Vegetables, Rhode Island Experiment Station Re ports, 1904 and 1905 ; Experiments in Growing Sumatra Tobacco Under Shelter-Tent, Bulletin No. 72, Pennsylvania Agricultural Experiment Station, 1905 ; Tent-Grown Berries and Celery, American Culturist, Vol. 67, p. 2, 1905.
Physiological references: Physiology of Plants, Vines, Oxford ; Pfeffer's Physiology of Plants, Vols. I, II and III, Ewart, Oxford ; Effect of Light upon Plants, MacDougal, Memoirs of the New York Botanical Garden, 1903.