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The Response of Plants to Illuminating Gas
Sarah L. Doubt
Vol. 63, No. 3 (Mar., 1917), pp. 209-224
Published by: The University of Chicago Press
Stable URL: http://www.jstor.org/stable/2469142
Page Count: 16
1. The following plants are admirably adapted for use as test plants for illuminating gas in greenhouses: Lycopersicum esculentum, Salvia splendens, Mimosa pudica, Ricinus communis, Datura Stramonium, and Dianthus Caryophyllus. The response of each is definite, striking, and not easily mistaken. 2. Traces of gas (50 ppm of air) cause the epinastic growth of the petioles of all these plants, with the exception of the last. The flower buds of the carnations are blighted by these amounts. One part of illuminating gas per 1000 of air causes leaf fall in the following plants: Lycopersicum esculentum, Salvia splendens, Mimosa pudica, Datura Stramonium, Ricinus communis, Coleus sp., and Hibiscus rosa-sinensis. Both the amounts (50 ppm of air and 1 part per 1000 of air) are far below the limit of odor. Repeated trials showed that it was impossible to detect less than 0.25 per cent of illuminating gas (1 part to 400 of air) by the sense of smell. 3. Amounts of ethylene corresponding to the gas mixture gave similar responses; 2 ppm of air caused epinastic growth of the petioles of Lycopersicum esculentum, Salvia splendens, Mimosa pudica, Ricinus communis, and Datura Stramonium; 8 ppm of air (equivalent to 200 parts of illuminating gas) caused some leaf fall in the 5 plants named. 4. Poa pratensis and Acer Negundo are very resistant to gas, having shown no response to concentrations injurious to all other forms tested. 5. The following plants are not noticeably injured by gas unless there is enough present to be detected by odor: Caladium esculentum, Lupinus perennis, Eriobotrya japonica, Phoenix canariensis, Conocephalus sp., Canna, Achyranthes lindini, Alternanthera sp., Cytisus canariensis, Polypodium, etc. 6. The following trees are rather sensitive to gas escaping into the soil: Pyrus Malus, P. communis, Fraxinus americana, Ulmus americana, Sambucus canadensis, Grevillea robusta, Catalpa speciosa, Populus deltoides, and Tilia americana. Apple, pear, ash, elm, Catalpa, and Sambucus showed proliferation tissue in the cortex of the stems below the surface of the ground. Elm, ash, and cottonwood showed longitudinal cracks in the bark just above the surface of the ground. 7. The following bedding plants are injured by gas escaping into the soil: Lycopersicum esculentum, Salvia splendens, Ricinus communis, and Chrysanthemum hortorum. Chrysanthemum is killed outright; the others drop their leaves or show epinastic growth of the petioles. 8. Young trees at least are injured by leakage of illuminating gas too slight to be detected by odor. The foliage shows no injury, and one would not be likely to suspect gas poisoning from the appearance of the tree above ground. Judging from my results with trees, their killing by illuminating gas is a very slow process, going on for months or years. It is certain that enough gas to cause an odor in the vicinity of trees would be enough to injure them seriously.