ECONOMIC WOODS OF THE UNITED STATES 



a^ Pores in early wood in few (1 -3) tows^ usually not 

 crowded; transition to smaller pores of late wood 

 abrupt. Pores in la te wood very small , with thin walls 

 and angular outlines (Plate II, Mg. 5) ; numerous, 

 crowded, not open, appearing as irregular, grayish 

 radial bands widening outward ; tyloses abundant in all 

 pores. Large rays often very high, maximum 5 inches. 

 , .._..- White Oak Group. 



a^ Radial bands of small pores comparatively broad, 

 more or less fan-shaped, often joined tangentially. 

 White Oak. Quercus alba L. (C, N) (Frontispiece)"'; 

 Bur Oak. macrocarpa Michx. (C, N) (Fig. 14); Post 

 Oak. minor Sarg. (C, A, S); Chestnut Oak. prmws* 

 L. (N, C)"^• Overcup Oak. lyrata Walt. (C, S); 

 Diu-and Oak. breviloba Sarg. (S). 



b^ Radial bands of small pores comparatively narrow 

 and seldom joined tangentially. Swamp Wliite Oak. 

 Q. platanoides (Lam.) Sudw. (N, C); Cow Oak. 

 michauxii Nutt. (C, S). 



b' Pores in early wood mostly in several (3-5 ) rows, 

 crowdefff traSSKonT^to smSlteT^ores in late \vood 

 gradual. Pores in late woqd_compa£atJTelyJa£gej_with 

 thick walls" and^circuTar outlines"XPlate" 117 Fig. 6); 

 rather few, not crowded, open, usually visible to un- 

 aided eye. Tyloses usually scarce or wanting, some- 

 times abundant (esp. in Q. marilandica) . Larg e ray g 

 comparatively low, rarely 1 inch high. 

 - " ~~ Black or Red Oak Group.* 



a^ Radial bands of small pores comparatively broad, 

 often branched. Pin Oak. Q. palustris Muench. (C) ; 

 Water Oak. nigra L. (S, C) ; Shingle Oak. imbricaria 

 Michx. (C, N); Spanish Oak. digitata Sudw. (S, C); 

 Turkey Oak. catesbcd Sudw. (S); marilandica 

 Muench. (C, S). 



b^ Radial bands of small pores narrow, mostly un- 

 branched. Red Oak. Q. rubra L. (C, N); Spotted 

 Oak. texana Buckl. (C, S); Black Oak. velutinaham. 



* For Evergreen Oak group see "Diffuse-porous Woods." 



