1895.] Anatomical Characters of N. Am. Gramineae. 363 
freer from warts, many of the epidermal cells being entirely 
smooth, and the thorn-shaped expansions are not so numer- 
ous in this species. Long hairs were observed to be charac- 
teristic of the variety depauperata of L, hexandra, and the 
base of these hairs showed a distinct constriction of the inner 
cell-wall (fig. 3). The hairs occurred especially on the in- 
L. monandra; the presence of such small bundles on the su- 
three different degrees of development in the mestome bun- 
dles of these species and they are characterized in the same 
way as those of L. oryzoides. A thin-walled parenchyma 
sheath is present in those of first and second degree, and 
is generally colorless, except in L. lenticularis, where chloro- 
phyll was observed in the sheath of all the bundles, though not 
in the median ones. The small ventral mestome bundles are 
merely surrounded by a mestome sheath. Concerning this 
sheath (the mestome sheath), it was observed to be present 
in all the bundles of the species in question, and consists of 
more or less thick-walled cells, forming a ‘closed ring around 
the leptome and hadrome. In L. Virginica and L. hexandra, 
however, the mestome sheath is rather thin-walled, even in 
the largest, the median bundle; the variety depauperata had, 
nevertheless, a distinctly thick-walled mestome sheath. 
The leptome and hadrome are well differentiated in the 
largest bundles, where they are separated from each other by 
a single or sometimes double layer 0 
parenchyma, as in L. lenticularis. The smaller mestome 
bundles, those of second degree, have the hadrome part less 
developed, and have no layer of thick-walled mestome paren- 
chyma. The ventral bundle is still more reduced and con- 
