1905] HOLM—MUNROA SQUARROSA 13% 
leptome and hadrome. Common to both is a thick-walled mestome 
sheath, but the parenchyma sheath is developed only on the outer 
face of the peripheral bundles, thus bordering on the palisades, being 
quite large-celled and containing chlorophyll of a somewhat bluish- 
green color. This parenchyma sheath is thus restricted to this 
particular portion of the peripheral mestome bundles in the upper 
part of the culm, where palisades occur, and is entirely absent in all 
the others. The inner portion of the culm is occupied by a thin- 
walled pith, which is broken in the center. 
Characteristic features of the culm, therefore, are the small develop- 
ment of chlorophyll-bearing parenchyma in the shape of palisades 
and as an incomplete parenchyma sheath, and the predominating 
chlorophyll-less cortical parenchyma which evidently has the function 
of storing water. The stereome is well represented, being thick- 
walled and constituting heavy layers both in the ridges and inside 
the cortex. 
THE LEAF.—The leaf blade is furrowed on both faces, deepest 
on the ventral, and covered with small obtuse papillae and somewhat 
larger prickle-like projections like those observed on the culm. The 
midrib is hardly larger than the other nerves, the blade thus being 
nearly flat and of the same thickness throughout. Stomata occur 
on both faces of the blade along the sides of the furrows, their guard 
cells being level with epidermis. While the cells of epidermis are 
small and quite thick-walled on the dorsal face of the leaf, those of 
the ventral are larger and developed as bulliform cells in the furrows 
between the mestome bundles. 
The parenchymatic tissues of the leaf consist of a colorless water- 
Storage tissue, which is located in the furrows beneath the bulliform 
cells, and consisting of three or four strata. There is also a chloro- 
phyll-bearing tissue, developed as one layer of palisades surrounding 
the mestome bundles and radiating from them. Similar palisade 
cells were also noticeable in the upper portion of the culm, and 
bordering on the incomplete parenchyma sheath. 
The mestome bundles are all orbicular in transverse section, and 
Possess a complete green parenchyma sheath besides a mestome 
sheath, which is somewhat thick-walled in the larger bundles. The 
leptome and hadrome are well differentiated in all the nerves, espe- 
