The Trees of Vermont 207 



d. Rays (cross) uniform, all of them more or less equal in 

 size (see note below^). 



e. Wood-parenchyma cells (cross) forming continuous or 

 somewhat broken, tangential lines or bands, scarcely 

 visible with a lens; wood light and soft. 

 /. Wood elements (cross) alternating with parenchyma 

 elements in a tier-like arrangement; vessels (tangential) 

 with spirals; rays (tangential) very narrozv, slender- 

 tapering; color light brown to nearly white, 



Tilia americana, p. 231. 

 ff. Wood elements (cross) not alternating with paren- 

 chyma elements in a tier-like arrangement, hut confined 

 to 2-4 rows of flattened cells at the outer limit of the 

 grozvth ring; vessels (tangential) zvithout spirals; rays 

 (tangential) rather zvide, abruptly-tapering ; color 

 bluish to the more common yellow-brown, often 



striped Liriodendron tulipifera. 



ee. Wood-parenchyma cells (cross) not forming tangential 

 lines or bands ; wood moderately heavy and hard. 

 /. Ray cells (radial) about as long as high; vessels 

 (longitudinal) plugged at intervals with dark red gum; 

 color rich red-brawn or wine. 



g. Rays (cross) distinct to the naked eye; pith flecks 

 (cross) usually absent; pores (cross) large and con- 

 spicuous under a hand lens. 



h. Pores (cross) of the spring wood larger and more 

 numerous than those of the summer wood ; larger 

 rays (tangential) 3-4-scriate ; wood rather soft, 



Prunus nigra. 

 hh. Pores (cross) of the spring wood not noticeably 

 larger nor more numerous than those of the sum- 

 mer wood; larger rays (tangential) 6-8-seriate; 



wood rather hard Prunus serotina. 



gg. Rays (cross) barely visible to the naked eye ; pith 

 flecks (cross) usually present, often prominent; 

 pores (cross) rather small and inconspicuous, even 

 under a hand lens Prunus pennsylvanica. 



1 The genus Crataegus apparently belongs here ; but the wood varies so greatly 

 and is of so little importance commercially that no attempt has been made to 

 incorporate it within the key. 



