. Botanical gazette. Plants. I9I91 WEAVER &- MOGENSEN—TRANSPIRATION 405 The midwinter losses, actual and relative, are just as marked as they were in the case of the yellow pines. During the period December 19 to February 7 the total average loss was only 2 .8 gm., an amount which, compared on the daily basis, is only 1/169 of that lost during the autumn period (September 26 to October 17). Abies grandis Two batteries of white firs were used. One consisted of eight 2-year-old seedlings in containers inches in diameter by inches deep, and the other of eight 4-year-old trees in conta
. Botanical gazette. Plants. I9I91 WEAVER &- MOGENSEN—TRANSPIRATION 405 The midwinter losses, actual and relative, are just as marked as they were in the case of the yellow pines. During the period December 19 to February 7 the total average loss was only 2 .8 gm., an amount which, compared on the daily basis, is only 1/169 of that lost during the autumn period (September 26 to October 17). Abies grandis Two batteries of white firs were used. One consisted of eight 2-year-old seedlings in containers inches in diameter by inches deep, and the other of eight 4-year-old trees in containers inches in diameter and 9 inches Fig. 5.—Average daily losses in grams from eight 3-year-old jack pines; September 26 to December 19, 1917. The younger plants were growing in soil with an available water content ranging from 6 to per cent. All were winter killed. As this did not occur until January or February, the transpiration losses up to that time are rehable. About January 15 the leaves began to drop off badly, but the leaf area of several of the plants was determined without removing the leaves, and before defoliation had begun. This was accomplished by determining the number of leaves, their lengths, and average diameters. Three of these seedlings had leaf areas of , , and sq. dm. respectively. These plants are shown in fig. 11. This picture was taken late in February after many of the leaves had fallen. Because of an accident to the top of one tree, it was 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 Hanover, Ind. : J. M. Coulter
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