OF THE EASTERN UNITED STATES 351 



lower face. Many of the mesophyll cells bordering the mid rib and 

 lateral veins show rosettes of calcium oxalate. Both surfaces show 

 numerous crypts containing glandular peltate hairs of two kinds, viz.: 

 golden yellow and reddish. Of these, the golden yellow variety are by 

 far more numerous. They consist of a pedicel or stalk two layers thick 

 and 3-4 cells high with a balloon-shaped multi-cellular head containing 

 oil and resin. The reddish variety are by far fewer and possess a stalk 

 portion four layers thick and two cells high with a bowl-shaped multi- 

 cellular head containing a small mass of resin. Simple unicellular tri- 

 chomes are found on both lower and upper epidermis. 



First pair of foliage leaves of M. CaroUnensis 

 The upper epidermis is composed of cells whose vertical walls appear 

 more wa\y in surface view than those of M. cerifera. The outer walls 

 of these cells have a mean measurement of 63.34 fx x 33.46 ix. The cells 

 directly over the veins show rectilinear walls and are slightly elongated 

 in the direction of the vein. 



The lower epidermis possesses cells whose vertical walls are indeed 

 more wavy than those of the upper epidermis and whose outer walls 

 show a mean measurement of 54.87 n x 23.30 n. Numerous stomata are 

 present among the epidermal cells of this surface. These are surrounded 

 by 5-8 neighboring cells. 



The mesophyll resembles that seen in the first pair of foliage leaves of 

 M. cerifera with the exception that it is only about half as wide, shows 

 more loosely arranged paHsade cells, and has fewer scelerenchyma ele- 

 ments below the mid rib and nerves. 



The upper surface shows fewer crypts than that of M. cerifera and 

 both surfaces are devoid of reddish glandular hairs with bowl-shaped 

 heads. Both surfaces however possess the golden-yellow glandular 

 hairs with balloon-shaped heads. The unicellular simple hairs are more 

 numerous than on either M. cerifera or the hybrid {M. cerifera xM. 

 CaroUnensis). 



First pair of foliage leaves of M. Macfarlanei {M. cerifera x M. Caro- 

 Unensis 

 The first pair of foliage leaves of the hybrid shows histological pecu- 

 liarities which in several respects are intermediate with those of both 

 of its parents— M. cerifera and M. CaroUnensis. For instance, the cells 

 of the upper epidermis in surface view have their vertical walls more 

 wavy than those of M. cerifera, less wavy than those of M. CaroUnensis, 

 Their outer walls have a mean measurement of 41.27 /x x 26.95 /x, while 



