The Trees of Vermont 205 



/. Pores (cross) of summer wood solitary, rarely grouped, 

 not forming short, tangential lines; wood parenchyma 

 (cross) forming more or less continuous, tangential 

 lines as distinct, or nearly so, as the rays; tyloses {tan- 

 gential) .present Carya, p. 229. 



ff. Pores (cross) of summer wood usually grouped, for the 

 most part forming short, tangential lines ; wood paren- 

 chyma (cross) not forming continuous, tangential lines; 

 tyloses {tangential) absent. 



g. Pores (cross) of spring wood 1-2 rows deep, forming 

 a narrow zone not over one- fourth the width of the 

 growth ring. . Fraxinus, pennsylvanica lanceolata. 

 gg. Pores (cross) of spring wood 3-5 rows deep, form- 

 ing a hroad zone one-third to one-half the width of 

 the growth ring. 



h. Pores (cross) of summer wood joined by zvood 

 parenchyma, forming short or more or less ex- 

 tended, tangential lines ; wood hard and strong. 

 i. Lines of pores and wood parenchyma (cross) in 

 summer wood short and broken, mostly near the 

 periphery of the growth ring {occasionally absent 

 or very indistinct) . .Fraxinus americana, p. 225. 

 a. Lines of pores and wood parenchyma (cross) in 

 summer wood long, more or less extended, 

 usually well distributed through the growth 



ring Fraxinus pennsylvanica. 



Jill. Pores (cross) of summer wood not joined by 

 wood parenchyma, rarely forming tangential lines ; 



wood soft and weak Fraxinus nigra. 



dd. Pores (cross) of summer wood small, but distinct, grouped 

 or more or less confluent, or joined by wood parenchyma, 

 to form wavy or branching, more or less extended, radial or 

 tangential lines. 



e. Pores (cross) of summer wood arranged in radial, 

 branching lines (when very crowded, radial arrangement 

 somewhat obscured) ; pores (cross) of spring wood 

 plainly visible to the naked eye at a distance of two feet, 

 strongly oval or elliptical, occupying nearly half the 

 growth ring Castanea dentata. 



