104 ECONOMIC WOODS OF THE UNITED STATES 



b" Pores very small, indistinct to unaided eye. 

 Woods fine-textured and straight-grained; 

 lighter-colored than preceding. Sp. gr. .46- 

 .04. Paper, White * or Canoe Birch, B. 

 popyrifera Marsh. (N, Rn, Pn)^; Gray 

 Birch, B. populifolia Marsh. (N). 



b^ Woods mostly cross-grained, tough to split. 

 Growth rings usually indistinct. Wood paren- 

 chyma scattered, not in tangential lines or terminal. 



a^ Wood very dense; sp. gr. about .75. Color 

 reddish-brown or roseate; sapwood yellowish. t 

 Pores minute, well distributed, very numer- 

 ous. Vessels without spirals; bordered pits round; 

 perforations simple; pits into ray cells half-bordered. 

 Rays 3-4 cells wide; homogeneous. Wood fibres with 

 numerous large bordered pits. Apple, Pyrus molus 

 L. (Int.)^7 



b^ Woods variable in density. The denser ones 

 colorless or light brown. Grain more inter- 

 locked than preceding. Rays 1-5 cells wide; 

 heterogeneous. Vessels mostly without spirals; sca- 

 lariform bordered pits common; perforations sca- 

 lariform with many bars. Pita in wood fibres not 

 conspicuous. 



a^ Color reddish-brown, often with irregular 

 dark streaks producing "watered " effect on 

 smooth longitudinal surface; sapwood often 

 variegated. Lustre rather dull. Pores 

 minute, abundant, uniformly distributed; 

 tyloses present. Gum ducts occasionally 

 present in peripheral row. Wood mod- 

 erately hard to rather soft; inclined to 

 warp; sp. gr. .50-. 60. Vessels without spirals 

 except indistinctly on overlapping ends of seg- 



* The names "red birch" and "white birch" are often used commercially 

 to designate the heart wood and sapwood, respectively, of Belula lenla or B. 

 liUea. 



t In the use of applewood for handles it is customary to steam the sapwood. 

 This treatment produces a rich uniform color resembling that of black cherry. 



