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IOWA ACADEMY OP SCIENCES. 
plainly shows that it can adapt itself to di-fferent conditions of 
soil and moisture. 
PANICUM CAPILLARE. 
This species has a hairy appearance and is harsh to the 
touch. The epidermal cells (e) are large, the cuticle (c) and 
epidermal cell walls are thicker than in P. crus-galli and P. 
proliferum, but not so well developed as in the genus Sporobolus. 
The walls of the epidermal cells of the upper and lower sur- 
face of the leaf have small conical projections (cp). The end 
of the leaf terminates in a small thickened point; on the edges 
of leaf occurs a bundle of stereome (st). 
The bulliform cells do not vary much from the epidermal 
cells, they are somewhat larger, however, and vary in number 
from three to five, the middle cell being the largest. The 
carene (c') has one mestome bundle (m) differing from those of 
secondary veins only in that it is larger, and being open on 
both upper and lower side. The mestome bundles are of three 
types: first, those which are open both above and below, second, 
those which are open below, and third, those which are closed. 
The leptome (1) is separated from hadrome (h) by thick walled 
parenchyma (p). In this species the arrangement of mestome 
bundles is irregular, the number varies from forty to forty- 
three bundles in one leaf. There are from twenty to twenty- 
two bundles on each side of the carene, and of these, three on 
each side are of the first type, three of the second type and the 
remaining of the third type. In the closed mestome bundles 
the leptome and hadrome are not so well developed as in 
those which are open. The stereome occurs on the upper and 
lower surface of all open mestome bundles, while in those 
which are closed it is found sometimes on the upper surface 
and sometimes on the lower surface, and sometimes it is entirely 
wanting. It consists of from two to four rows, bordering 
immediately on the chlorophyll bearing parenchyma (c bp). 
At the sides of the leaf well developed stereome occurs for the 
purpose of protection. 
The mesophyll (mes) consists of elongated cells joining the 
chlorophyll bearing parenchyma. Between the mestome 
bundles surrounded by the mesophyll, we have colorless 
parenchyma. 
PANICUM PROLIFERUM. 
In this species the epidermal cells are much smaller than in 
P. capillare, and the conical projections (c p) are found more 
