Bui. 606, U. S. Dept. of Agriculture. 



Plate IV. 



Post Oak, A White Oak (Radial Section, Magnified 50 Diameters). 



SP, springwood; SW, summerwood; MR, medullary ray; V, pores or vessels; X, wood pros- 

 enchyrna (fibers, etc.); T, tyloses. 



