ECONOMIC WOODS OF THE UNITED STATES 87 



b 1 Rays of two kinds: (1) large and conspicuous,* showing 

 as broad flakes on radial surface and as distinct lines 

 on the tangential; (2) very fine and inconspicuous, 

 mostly invisible without lens. (See Plate III, Fig. 1.) 

 Wood hard and heavy; usually very tough and strong; 

 sp. gr. .65-. 90. Odor of fresh wood characteristic. 

 (Microscopic features given above also apply here, except as to 

 size of rays.) Oak. | 30 



a 2 Pores in late wood individually distinct under lens 

 and few enough to be readily counted; arranged 

 mostly in fairly definite radial rows (except in nar- 

 row growth rings). Pores in early wood usually 

 crowded in a broad zone and becoming gradually 

 smaller outward (occasional exceptions). All pores 

 usually open; sometimes partially or wholly filled 

 with tyloses. Ray lines on tangential surface usually 

 short (rarely exceeding 1 inch), and more or less in- 

 terrupted by wood fibers. Color of wood typically 

 pale reddish-brown, deeper near knots. Pores in late 

 wood are thick-walled and more or less circular in outline. 

 (Plate II, Fig. 6.) Black and Red Oak Group. 

 Red Oak, Quercus rubra L. (C, N) ; Black or Yellow 

 Oak, Q. velutina Lam. (C, N); Spotted Oak, Q. 

 texana Buckl. (C, S) ; Spanish Oak or Southern Red 

 Oak, Q. digitata Sudw., or Q. falcata Michx. (S, C); 

 Scarlet Oak, Q. coccinea Muench. (C, N) ; Pin Oak, 

 Q. palustris Muench. (C) ; Black Jack, Q. marilandica 

 Muench. (C, S) ; California Black Oak, Q. californica 

 (Torr.) Coop. (P) ; Water Oak, Q. nigra L. (S, C) ; 

 Laurel Oak, Q. laurifolia Michx. (S) ; Shingle Oak, 

 Q. imbricaria Michx. (C, N) ; Willow Oak, Q. phellos 

 L. (S). 



* Occasional specimens of branches or of rather small stems are found 

 which have few or no large rays. Oak wood is quite distinct, however, even 

 when this prominent feature is wanting. 



f The author is of the opinion that the features so far recognized as con- 

 stant in the woods of the oaks will permit separation into general groups only. 

 Fortunately, this classification corresponds very closely to the technical 

 properties of the woods and this fact renders specific distinctions of much less 

 importance. 



