HOLM—ALPINE GRAMINEAE 441 
protected by the more ample covering of papillae or hairs, and also by 
the greater depth of the furrows. In the leaves of the lowland species 
the stereome is better represented, the bulliform cells generally larger, 
and frequently accompanied by several strata of a colorless tissue, 
the so-called water-storage tissue, which is not developed in the alpine 
species. But in the chlorenchyma of the Gramineae from the plains 
and prairies we find a more or less homogeneous tissue of palisades 
occupying the position described above. Finally the fact must be 
mentioned that the stomata being most frequent on the ventral face of 
the leaf is a feature the alpine Gramineae have in common with nearly 
all those which I have examined from the lowlands, and especially 
those from the plains and prairies, with the exception of Sporo- 
bolus, Munroa, and Calamovilfa. In the woodland types of Muehlen- 
bergia the stomata are almost equally distributed on both faces of the 
leaf blade; while in the species of the same genus from dry, rocky 
mountain slopes, the stomata are confined to the ventral face and pro- 
tected by the folding of the blade. In species from wet soil, meadows, 
or swamps, the stomata are most frequent on the dorsal face in Leersia; 
while in Amphicarpum from moist pine barrens they are distributed 
over both faces, though most numerous on the ventral; in Uniola 
latifolia from shaded slopes the stomata occur only on the ventral face, 
and this same disposition is to be found also in Pleuropogon Sabinei 
from arctic swamps. Duvat-Jouve, who has examined a large 
number of Gramineae," speaks of the difficulty of giving any precise 
information about the distribution of stomata in this family. He 
observed also that the ventral face of the blade is sometimes the only 
One where the stomata occur, but at the same time he noticed that a 
torsion of the leaf took place, thus exposing the dorsal face to the sun 
instead of the ventral. In this way the stomata become well pro- 
tected, but in our alpine types the only protection seems to depend 
Upon = folding of the blade, conduplicate or with the margins 
involut 
The leaf structure of alpine plants has been described and explained 
by several authors, but the Gramineae have been neglected, and 
evidently because the narrow leaves appear to be more uniform in 
ut os Pech sin Histotaxie des feuilles de Graminées. Ann. Sci. Nat. Bot. 
E a 
