152 IOWA ACADEMY OF SCIENCES. 



on each side. The strongly involute character of the leaf is 

 due to the bulliform cells. 



The carene (c') is occupied with one mestome bundle; this 

 bundle is somewhat different than the others, as it is sur- 

 rounded on the upper side by chlorophyll bearing parenchyma 

 while the lower side contains stereome. 



The mestome bundles on right and left of carene are entirely 

 closed (i. e. , entirely surrounded by chlorophyll bearing paren- 

 chyma). This species is provided with three different types of 

 mestome bundles; the first occurs in carene; this has stereome 

 on lower side in contact with leptome; the second, those which 

 have stereome both on lower and upper side, in contact with 

 leptome and hadrome; and third, those that are entirely closed. 

 Those that are entirely closed occur alternate with those having 

 stereome on upper and lower surface. As to the mestome 

 bundles, there are, in this species, five on left side of the carene 

 and seven on the right side. On the left, the leaf terminates 

 with one closed mestome bundle. The right side of the leaf 

 terminates with three mestome bundles. The mestome bundles, 

 except those at the tip of the leaf, are separated from each 

 other by the bulliform cells and three or four layers of colorless 

 parenchyma. The uncolored parenchyma is more conspicuous 

 near the median nerve, where it is quite strongly developed. 

 In this species the mesophyll does not occur between the 

 bundles but is found only in immediate contact with chlorophyll 

 bearing parenchyma (c b p). 



The uncolored parenchyma cells are in immediate contact 

 with stereome. The mestome bundles are entirely closed and 

 do not have leptome (1) and hadrome (h) so well developed as 

 in the other bundles. The leptome in the open bundles (i. e. , 

 having stereome in contact with both leptome and hadrome) 

 seem to be in two parts, there being a depression on upper side 

 of leptome. 



The stereome occurs on the upper side of all bundles, and 

 also on the lower side of all bundles except those which are 

 entirely closed. 



Below the uncolored parenchyma connecting the mestome 

 bundles we find the stereome. The stereome occupies a prom- 

 inent place on the sides of the leaf, forming on the left two 

 triangular groups of cells separated by two layers of uncolored 

 parenchyma. On the right side three such groups occur 

 between the last four mestome bundles. 



