Supposed Hybrid of the Black and Shingle Oaks 327 



zigzag than in velutina, and closely simulates the condition in 

 imbricaria. The medullary cells are usually broad, as in velutina, 

 although occasional narrow ones are to be found. The ray cells 

 tend to be rectangular, with straight thick walls, here again as 

 in velutina. The wood parenchyma cells yary widely in size, 

 both the large ones of velutina and the smaller ones of imbricaria 

 being here present. 



SUMMARY OF MICROSCOPIC STUDIES 



From these anatomical studies it appears that, while certain 

 features show remarkable uniformity in form and structure, 

 differences do appear in the size, number, and arrangement of 

 parts. In all these respects it is seen that Leana resembles either 

 imbricaria or velutina, rarely occupying an intermediate position 

 between them. From the table it will be seen that Leana re- 

 sembles velutina in the distinctly e features of the following 

 characters : ar nual ring, spring and summer wood, broad rays, 

 broad and narrow ray cells, pith (arrangement of cells), wood 

 parenchyma, wood fibers, yessels (distribution), protoxylem 

 (arrangement), and sclerenchyma of bast. It resembles im- 

 bricaria in pith cells (size), fiye bands, narrow medullary rays, 

 some of the wood parenchyma cells, yessels (size), and in tyloses. 



Penhallow'* shows in an anatomical study of Teas In^brid Catalpa 

 that the structural features of the two parents are faithfully 

 transmitted to the offspring. If what Penhallow found to be 

 true for Catalpa obtains in oaks, we haye a right to conclude that 

 resemblances such as appear between the oaks in question haye 

 a significance in demonstrating actual relationship. In other 

 words, these resemblances furnish a strong evidence of the hybrid 

 nature of Lea's oak. 



Comparison With the Type Tree and Others 



Leayes of the t\pe tree in general resemble yery closely those 

 from the Cedar Point trees, although differing in certain respects. 

 The latter leayes are often more deeply lobed, and their bases 

 tend to be less obtuse than the former. On the other hand, 



^^American Naturalist, vol. xxxix, No. 459, pp. 113-136, 1905. 



