94 ECONOMIC WOODS OF THE UNITED STATES 



a* Lines of pores in late wood short, narrow, com- 

 posed of few pores and considerable wood paren- 

 chyma; mostly near outer margin of growth 

 ring; occasionally absent or very indistinct in 

 narrow rings. White Ash, Fraxinus americana 

 L. (C, N).-'^ 



b^ Lines of pores in late wood long, narrow, promi- 

 nent, composed of abundant wood parenchyma 

 and inconspicuous pores; usually well distrib- 

 uted. Blue Ash, F. quadrangulata Michx. (C); 

 Red Ash, F. pennsylvanica Marsh. (N). 



b^ Pores in early wood in rather narrow zone; fairly 

 numerous. Lines of pores in late wood quite 

 long and conspicuous; well distributed. Green 

 Ash, F. lanceolata Borh. (C, N, S); Pumpkin 

 Ash, F. profunda Bush. (C). 



b^ Wood parenchyma in numerous fine concentric lines 

 independent of pores. Pores in late wood sometimes 

 approaching in size those in early wood which are not 

 abundant and usually arranged in a very irregular zone. 



a? "Ripple marks" (see p. 39) plainly visible on tan- 

 gential section; wavy; 60 to 80 per inch. Lines of 

 wood parenchyma indistinct without lens; finer 

 than the rays. Pores open. Color of heartwood 

 of old trees dark brown to black, often streaked; 

 sapwood white or gray. Wood very hard, heavy 

 and strong; sp. gr. .79. Rays in horizontal seriation; 

 fairly uniform in height; 1-2 (rarely 3) cells wide; cells 

 large ; heterogeneous. (Plate IV, Figs. 4, 5.) Vessels without 

 spirals; perforations simple; pits into ray cells half-bordered. 

 Persimmon, Diospyros virginiana L. (S, C).^^ 



b- " Rippl(> marks " absent. Linos of wood parenchyma 

 distinct as the rays; visible without lens. Pores 

 partially or wholly closed with tyloses. Color of heart- 

 wood brown to reddish-brown ; sapwood white, often 

 with pinkish tinge and sometimes with dark reddish 

 or rusty streaks. Rays irregularly disposed; not 

 uniform in height or shape; 1-5 cells wide; cells small; 



