100 ECONOMIC "WOODS OF THE UNITED STATES 



a^ Wood elements not in tier-like arrangement. 

 Vessels without spirals; perforations scalari- 

 form; often with scalariform bordered pits. 

 Rays light red or pink in color; hetero- 

 geneous. Color pale reddish brown or pink- 

 ish, sometimes with greenish hue. Wood 

 very heavy, hard and tough. Dogwood. 



a^ Rays 1-7 cells wide, few to 80 cells high. 

 Cornus florida L. (N, C, S). 



b^ Rays smaller, 1-4 cells wide, few to 40 

 cells high. C. nuttallii Aud. (P). 



b^ Wood elements (except rays) in tier-like 

 arrangement, producing somewhat indistinct 

 cross-markings on longitudinal surface. Ves- 

 sels with spirals ; perforations mostly simple ; 

 bordered pits not scalariform. Rays color- 

 less, widely variable in size; small rays uni- 

 seriate, 10-15 cells high; large rays, 3-5 

 cells wide, 50-100 cells high; homogeneous. 

 Color light brown to nearly white. Wood 

 light, soft, compact, moderately strong. 

 Basswood.*' Tilia americana L. (N, C), 

 pvbescens Ait. (S, C), heterophylla Vent. 

 (A, C, S). 



b* Rays distinct ; fairly uniform in width, 1-3-seriate. 



a^ Wood with straight grain , usually lig ht and snfj^ 

 easy to work. Wood fibres with rather thin walls, 

 usually rounded; not in radial rows. Pores 

 crowded; tyloses absent. Outer limit of growth 

 ring composed of 2-4 rows of tangentially flattened 

 wood-parenchyma fibres with very thick radial 

 walls. Rays heterogeneous. 



a^ Vessels with round or elliptical bordered pits; 

 without spirals. Pores rarely in radial groups. 

 Rays mostly 3-seriate, few to 60, mostly 20-40, 

 cells high. Texture fine. Color variable from 

 deep iridescent bine tn the more c r^mmnn val- 

 lowish brown; often striped . Yellow Poplar or 



