326 Earl Harrington Foote 



The wood parenchyma cells and also the wood fibers average 

 somewhat larger in velutina, and the latter are not so straight. 

 The vessels show fewer tyloses. 



Radial. The pith cells in their vertical arrangement show 

 something of the regularity seen in imbricaria, but their greater 

 variability in size and form makes the rows of cells less even and 

 distinct, and the wavy zigzag character of these rows is more 

 pronounced. The pith ray cells average somewhat longer and 

 wider, and tend to be more strictly rectangular, with straighter 

 thicker walls. The wood parenchyma cells average somewhat 

 larger. 



LEANA 



Transverse (plate XIII, fig. 3; plate XIV, figs. 3, 6). The 

 pith cells in their arrangement present a fairly compact structure, 

 as in velutina, but in uniformity of size and shape they are more 

 like imbricaria. The uniseriate medullary rays are straight and 

 rather inconspicuous, thus resembling imbricaria. The cells, 

 however, are broader and more irregular, as they are in velutina. 

 The wood parenchyma is altogether velutina like, both in its 

 distribution and arrangement. The radial arrangement of the 

 wood fibers is maintained here, as in imbricaria despite the fact 

 that the numerous blocks of wood parenchyma would naturally 

 tend to break it up. Angular tracheids are abundant in the 

 spring wood, while a few roundish ones are to be found embedded 

 in the wood masses of the later growth. The vessels are alto- 

 gether velutina like, in abundance, distribution, and arrangement. 

 The protoxylem is perhaps somewhat less scattered than in 

 velutina, but shows none of the distinct massing characteristic 

 of imbricaria. In the bast of young stems the band of scleren- 

 chyma presents the deeply scalloped appearance of velutina. 



Tangential. The broad medullary rays of the younger stems 

 present in their interruption by obliquely running strands, a con- 

 dition closely resembling that in imbricaria. The narrow rays in 

 their number, size, character, arrangement and distribution, 

 are altogether like velutina, as are also both the wood parenchyma 

 and the wood fibers. Tyloses occur abundantly in the vessels 

 in some of the preparations studied. 



Radial (plate XIV, fig. 9). The arrangement in vertical 

 rows of the pith cells is more distinct and even, and less wavy and 



