210 Bulletin 194 



gg. Pores (cross) not abundant, solitary-scattering or in 

 remote, radial lines; growth rings (cross) sinuous; 

 pith flecks (cross) usually absent; wood parenchyma 

 (cross) forming distinct, tangential markings. 



Ostrya virginiana. 

 ee. Vessels {tangential) ivithont spirals. 



f. Rays (tangential) all alike, uniseriatc throughout or 

 nearly so; wood for the most part soft and light. 

 g. Pores (cross) of summer wood markedly smaller and 

 fewer in number than pores of spring wood, arranged 

 in more or less prominent, wavy, concentric lines ; 

 wood (radial) without silky luster; rays (radial) 

 zuith both upright and procumbent cells, 



Salix nigra. 



gg. Pores (cross) of summer wood not markedly smaller 



and fewer in number than pores of spring wood, not 



arranged in more or less prominent, wavy concentric 



lines; wood (radial) with silky luster; rays (radial) 



with only procumbent cells Populus, p. 229. 



ff. Rays (tangential) not all alike, but some broad, 1-6- 

 seriate; wood mostly hard and heavy. 

 g. Growth rings (cross) indistinct, very narrow and 

 crowded together; tyloses (longitudinal) presen/t; 

 larger rays (tangential) 1-2- , occasionally 3-seriate, 



Nyssa sylvatica. 

 gg. Growth rings (cross) distinct, not very narrow and 

 not crowded together; tyloses (longitudinal) absent; 

 larger rays (tangential) 3-6-seriate. 

 h. Rays (cross) just visible to the naked eye with close 

 scrutiny; pores (cross) more or less uniformly dis- 

 tributed, neither larger nor more numerous in the 

 spring wood; pith flecks (cross) rare or wanting; 

 wood heavy and hard. 



i. Larger rays (tangential) 3-5-seriate; pores 

 (cross) visible to the naked eye with close 



scrutiny Betula lenta. 



n. Larger rays (tangential) 1-2- , sometmes 3- 

 seriate; pores (cross) hardly visible to the naked 

 eye with close scrutiny. . . .Betula lutea, p. 227. 



