IOWA ACADEMY OF SCIENCES 
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and superior surfaces of the bundle. In the carene, leptome and 
hadrome are separated from each other by thick* walled cells. 
The cells in leptome are somewhat more thick- walled than in 
hadrome. 
In some of the mestome bundles of third type the hadrome is 
not so well developed; the intercellular space is not evident. 
This is not the case with mestome bundles of first type, in 
which this space is very conspicuous. The leptome is in direct 
contact with stereome, but hadrome is separated by thin- walled 
parenchyma cells. The bundles of second type are small; lep- 
tome and hadrome are but slightly developed, most of the bun- 
dles containing only thick- walled cells, while occasionally there 
is a bundle which has an indication of one or two pitted vessels. 
In the mestome bundle of third type, the leptome is separated 
from the stereome by thin- walled parenchyma cells. 
In Festuca elatior var. pratensis, as in Lolium perenne, a thin- 
walled parenchyma sheath surrounds all bundles of the second 
type, but in all cases thick- walled cells form a closed sheath 
around leptome and hadrome just inside of parenchyma sheath. 
Stereome. — This consists usually of six cells at the margins 
of leaf and occurs on superior surfaces of all bundles of the 
first and third types, and occasionally on superior surface of 
the mestome bundles of second type. It is not, however, 
strongly developed. Greatest development is reached on 
superior and inferior surfaces of mestome bundles of carene. 
Mesophyll . — This is found between all mestome bundles. The 
mestome bundles are found not so close as in Lolium perenne. 
The cells are smaller. The smaller occur on superior face. 
The epidermal cells of stereome region are thick- walled. 
FESTUCA TENELLA WILLD. 
(PI, ix, Pig. 3; PI. X, Pigs. 5 and 6.) 
Epidermis . — The epidermis is as strongly developed as in 
Festuca elatior var. pratensis though not as large as in Lolium. 
The smaller cells occur on superior surface. The cuticle is 
thicker on inferior surface than on superior surface. The epider- 
mal cells covering the stereome are thick- walled and not as 
large as the other epidermal cells. 
This dry soil grass has involute leaves and, as Hackel says: 
“In grasses that do not have such fan-shaped cell groups (bulli- 
form cells) the blade remains always folded or rolled up, or at 
least open but a little.” Bulliform cells do not occur, or only^ 
as slight differentiation of epidermal cells. 
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