102 ECONOMIC WOODS OF THE UNITED STATES 



with spirals; perforations simple. Rays 1-2, occa- 

 sionally 3, seriate; few to 20, occasionally 40, 

 cells high. Wood parenchyma in indistinct tan- 

 gential lines barely visible with lens. ^GrQ^th 

 rings sinuous , quite distinct. Color light brown; 

 sapwood with pinkish hue. Wood very heavy, 

 hard, tough, difficult to split. Hornbeam. Ostrya 

 virginiana Koch. (N, C) (Plate V, Fig. 6). 



b^ Pores numerous, fairly uniform in size and dis- 



tribution throughout growth ring, solitary or in 



adial groups of 2-6. Vessels without spirals; 



lerforation scalariform. Rays variable. Growth 



ings regular in outline. 



* Wood straight-graine^j fissile, easy to work. 

 Grnwt.h r ings usually Hiat.inp.t Vessels densely 

 pitted with extremely small bordered pits with 

 slit-like openings. Rays homogeneous. Wood 

 parenchyma scattered, sometimes in broken 

 tangential lines in outer late wood. 



a' Rays 1-5-seriate, occasionally wider. Pores. 



usually distinct to unaided eye. 



a° Wood heavy, hard, and strong. Pores 

 moderately abundant . Wood fibres with 

 thick walls. Rays widest of genus, deeply 

 colored. Pith flecks rare. Color brown 

 tinged with red, often deep and hand- 

 some. Sweet, Black, or Cherry Birch. 

 Betula lenta L. (N, C) (Plate V, Fig. 5). 



b^ Wood rather light and soft , moderately 

 strong. Pores very numerous, larger 

 than in preceding. Wood fibres with 

 rather thin walls. Pith flecks common. 

 Color hrnwn. Red or River Birch. B. 

 nigra L. (S, C, N). 



b' Rays 1-2, sometimes 3, seriate. Pores very 

 small, indistinct to nnpided , p yp 



a^ Wood rather heavy, hard, and strong . 

 Pores moderately abundant. Sapwood 

 thin, light brown or yellowish. Pith 



