794 



MACROSCOPIC AND MICROSCOPIC CHARACTERS OF PLANTS. 



longer than broad, and with thick walls. The cells of 

 L. purpurata are larger than those of C. mossice; those 

 of the hybrid at the apex are between those of the parents, 

 but those at the middle are in the hybrid much shorter, 

 and at the base they are narrower than in the parents. 

 The average size of the cells for the whole leaf is in the 

 hybrid between those of the parents, but very much 

 nearer C. mossice. (Table J 17.) 



Sections of the lower epidermis were taken from the 

 same regions as those of the upper epidermis. The cells 

 are similar to those of the upper epidermis in shape and 

 thickness of walls. Those of L. purpurata are larger 

 than those of C. mossice, except at the base of the leaf 

 where they are a little shorter. Those of the hybrid 

 at the apex are between those of the parents in both 

 length and width and at the base in width ; but at the 

 middle are smaller than in either parent in both dimen- 

 sions, and also less in length at the base. The average 

 size of the cells for the entire leaf in the hybrid is less 

 in length than in either parent and between the two in 

 width, though much nearer C. mossice. (Table J 17.) 



TABLE J 17. 



Stomata are less numerous in L. purpurata than in 

 C. mossice, and more numerous in the hybrid than in 

 either parent. (Table J 18.) 



TABLE J 18. Number of stomala in a field on lower epidermis. 



L. purpurata: At apex 8; at middle 8.9; at base 5.6; average for entire 



leaf 7.5. 

 C. mossice: At apex 10.7; at middle 11.5; at base 7; average for entire 



leaf 9.7. 

 L.-C. canhamiana: At apex 11.2; at middle 12.6; at base 9.8; average 



for entire leaf 11.2. 



Transverse sections of leaves of the same age at a dis- 

 tance of 1 inch from the apex were made at the midrib 

 and at the first main vein from the midrib (Plate 30, figs. 

 181, 182, and 183). At the midrib, the upper epidermis is 

 composed of rectangular, rather thick-walled colls having 

 a very heavy cuticle on the outer face. The cells of L. 

 purpurata become smaller toward the midrib angle ; those 

 of C. mossice become greatly elongated ; and those of the 

 hybrid become elongated though not to such an extent 

 as in C. mossice. 



The cuticle on the upper epidermis in the hybrid 

 is much deeper than in either parent. (Table J 19.) 



TABLE J 19. 



* Proportion of phloem, L. purpurata, one-third; C. mossice, one- 

 sixth; L.-C. canhamiana, one-fourth. 



