IOWA ACADEMY OP SCIENCES. 
157 
strongly developed only on the upper surface of the leaf; they 
are much more numerous than in P. capillare, but not nearly 
so sharply defined. The cuticle (c) is not so strongly developed 
as in P. capillare. 
The bulliform cells vary from two to five, usually consisting 
of one large or two large central cells. The leaf is not so 
strongly involute in this species, but the bulliform cells (b) 
extend farther down into the mesophyll (mes) than in P. 
capillare. 
The carene (c^) has one mestome bundle (m), which is open 
at the lower side. There are from forty to forty-five mestome 
bundles in the leaf, the median beiag the largest. On either 
side of the carene are five small mestome bundles entirely 
closed , then occurs a secondary bundle on each side resembling 
the carene, only much smaller. The leptome is separated 
from the hadrome in the carene by thick- walled parenchyma 
cells (p). 
The mestome bundles are of two types; first, such as are 
open below, and second, those that are entirely closed. The 
closed are much more numerous than the open; only six or 
seven open in the whole leaf. The leptome (1) and hadrome 
(h) are not well developed in the small bundles. 
The mesophyll consists of elongated and somewhat loosely 
arranged ceils of variable size. One larger surrounds the 
chorophyll bearing (cbp) parenchyma cells and comes in con- 
tact with the stereome (st); the space between the mestome 
bundles and beneath the bulliform cells is also filled with 
them. 
The stereome is found on the lower side of all bundles, in 
contact with the parenchyma and epidermis, and also on the 
upper surface of ail the larger mestome bundles. 
PANICUM CRUS GALLI. 
The most obvious difference between P. crus-gabi and P. 
capillare is that in this species the leaf is not involute; the 
epidermal cells (e) are large; the cell wall and cuticle (c) is not 
so strongly developed but conical projections are found on both 
surfaces of the leaf. 
The carene has one mestome bundle (m). It differs from 
the other species studied in that the stereome is not in direct 
contract with the leptome (1) and hadrome (h) but is separated 
from them by two rows of thick walled parenchyma (p), while 
the leptome and hadrome are in direct contact with each other. 
