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The Medullary Rays of Cedrus
M. A. Chrysler
Vol. 59, No. 5 (May, 1915), pp. 387-396
Published by: The University of Chicago Press
Stable URL: http://www.jstor.org/stable/2468435
Page Count: 10
1. The medullary rays of Cedrus are provided with a margin which varies greatly in composition, being made up of tracheids and parenchyma in varying proportion, or devoid of marginal cells for considerable stretches. 2. Marginal parenchyma when present occurs at the limit of annual rings, and may also extend beyond this point so as to be more plentiful than ray tracheids. 3. The constant occurrence of marginal parenchyma cells at the limit of annual rings, and their close connection with resin cells, indicates that parenchyma has replaced tracheids in connection with secretion of the so-called resin. 4. The marginal cells in Cedrus show distinct evidence of being in a degenerating condition. 5. The medullary ray structure confirms the view that Cedrus stands intermediate between Pinus and Abies.