104 ECONOMIC "WOODS OF THE UNITED STATES 



mostly solitary, uniformly distributed; Vessels 

 with spirals. Color nale vellow to nearly 

 white. Lustrous. Texture very fine and uni- 

 formT Grain often wavy and somewhat inter- 

 locked. 



a^ Wood elements (including rays) in tier-like 

 arrangement, producing very distinct trans- 

 verse lines on longitudinal surface. 

 Buckeye. Msculus octandra Marsh. (C).^^ 



b^ Wood elements not in tier-like arrangement. 

 Ohio Buckeye. A. fifZaferoWilld. (C) (Plate 

 VI, Figs. 5, 6) ; Califomia Buckeye, calif ar- 

 nica Nutt. (Ps). 



b^ _ Rays indistinc t under lens; 1-25, mostly 10-15, 

 cells high, i'ores variable; in short radial 

 groups. Vessels without spirals. Grain usually 

 straight. 



a^ Rays heterogeneous. Pores minute, invis- 

 ible to unaided eye . Uolor pale reddish 

 Brown. Lustre dull. Black Willow. Salix 

 nigra Marsh. (N, S, C, Rs, Ps)." 



b^ Rays homogeneous. 



a^ Pores minute, invisible without lens. 

 Texture very fine. Lustre silky. Color 

 light brown to silvery white. Aspen. 

 Populus tremuloides Michx. (N, C, R, P).^* 

 Large Tooth Aspen, grandidentata Michx. 

 (N, C). 



b^ Pores small to minut e, t hose in earlv woo d 



' usually visible tolTnaided eve . Textu re 



Ijoarse. Lustre dull. Color pale, djj ll 



Drown, or grayish browft. Cottonwood. 



F- fieterophylla L. (S, C), trichocarpa 



T. & G. (P), deltoides Marsh. (N, C, S, R). 



