. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 16 BULLETIN 523^ U. S. DEPARTMENT OF AGEICULTUEE. by the contrast of the belt of springwood containing numerous large pores with that of the denser smnmerwood containing minute pores. The summerwood pores are arranged singly or in broken lines, the course of which is never radial. The pith or medullary rays are very minute and scai-cely distinct when viewed in cross section, which is an important distinguishing characteristic of the genus, but one which is also characteristic of osage orange and catalpa, the woods that
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 16 BULLETIN 523^ U. S. DEPARTMENT OF AGEICULTUEE. by the contrast of the belt of springwood containing numerous large pores with that of the denser smnmerwood containing minute pores. The summerwood pores are arranged singly or in broken lines, the course of which is never radial. The pith or medullary rays are very minute and scai-cely distinct when viewed in cross section, which is an important distinguishing characteristic of the genus, but one which is also characteristic of osage orange and catalpa, the woods that most closely resemble ash in structure. Osage-orange wood can be distinguished readily by its bright yellow color and by its very great hardness and weight. Catalpa wood, on the other hand, is light and soft and has the pores of its summerwood arranged in clusters, which is not the case in ash or osage Fig. 3.—Transverse sections of ash wood under small hand Icnse ; A, black asb ; B, white ash; C, green ash. Taken from Bulletin 10 of the Division of Forestry (1895), by Prof. Filibert Roth, It is difficult and often impossible to distinguish, with any degree of certainty, the wood of the different species of ash. (Pis. V and VI.) Determination of species on the basis of wood characteristics, therefore, is very unsatisfactory. The following points of difference •(fig. 3) in the important commercial series, as they appear under the magnifying glass, are taken from Forest Service Bulletin 10, " Timber," by Filibert Koth: ^ 1 rhotomlcrograpbs of slides made by A. Koeliler, of tlie Forest I'roducls 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 United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : Supt. of Docs. , G. P. O.
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