206 Bulletin 194 



ee. Pores (cross) of summer wood arranged, or joined by 

 zvood parenchyma, to form wavy or branching, tangential 

 lines; pores (cross) of spring wood not plainly visible to 

 the naked eye at a distance of two feet, not strongly oval 

 nor elliptical, not occupying nearly -half the growth ring. 

 /. Lines of summer-wood pores (cross) strongly wavy; 

 tyloses (tangential) mostly absent, not densely plug- 

 ging the vessels; wood not yielding a brown stain when 

 rubbed with a wet, white handkerchief ; growth rings 

 (cross) not very wide. 



g. Pores (cross) of spring wood in 3-many rows; pores 

 (cross) of summer wood small, forming thin, rather 

 broken and disconnected, tangential lines, not 

 strongly wavy ; heartwood chocolate-brown, 



Ulmus fulva. 

 gg. Pores (cross) of spring wood usually in a single row, 

 or nearly so; pores (cross) of summer wood large, 

 forming broad, mostly connected, tangential lines, 

 strongly wavy ; heartwood light brown or red. 

 h. Pores (cross) of spring wood large, plainly visible 

 to the naked eye at a distance of 6-9 inches, form- 

 ing a continuous row ; texture coarse ; wood hard 



to split Ulitius americana, p. 225. 



hh. Pores (cross) of spring wood small, not visible to 

 the naked eye at a distance of 6-9 inches, not form- 

 ing a continuous row, but the larger ones few and 

 rather widely separated ; texture medium ; wood 



fairly easy to split Ulmus racemosa. 



ff. Lines of summer- wood pores (cross) not strongly 

 wavy; tyloses (tangential) present, densely plugging 

 the vessels; wood yielding a brown stain when rubbed 

 with a wet, white handkerchief; growth rings (cross) 



very wide Robinia pseudo-acacia. 



bb. Growth rings (cross) not defined by zones of large pores in the 

 spring wood, but pores all the same size, or nearly so, scattered 

 more or less evenly through the growth ring, occasionally more 

 numerous and very often somewhat larger in the spring wood. 

 c. Rays (cross) usually plainly visible to the naked eye at a dis- 

 tance of 6-9 inches. 



