A study of some anatomical characters of North American 
Graminex. VY. 
THEO. HOLM. 
WITH PLATE XXVI,. 
The genus Leersia. 
In a previously published paper! we have described the 
leaf-structure of Leersia oryzoides, and we will now consider 
the other species of this genus, L. enticularis Michx., L. Vir- 
gtnica Willd., L. monandra Swtz., and L. hexandra Swtz. 
The anatomical structure of the leaf appears to be very 
uniform in this genus, and transverse sections of the midrib 
and the surrounding tissues show very few differences from 
what we have already mentioned for L. oryzoides. This uni- 
formity in structure is undoubtedly due to the fact that the 
species in question inhabit the same kind of localities, viz., 
borders of lakes, ponds, or swamps. Leersia hexandra, how- 
ever, very often grows in deep water, and therefore this spe- 
cies shows a greater development of the bulliform cells and 
the colorless parenchyma than any of the other species. __ 
The structure of the epidermis in regard to shape and size 
with the exception that L. hexandra (fig. 1), possesses groups 
of these cells between all the mestome bundles and on both 
‘Bor. Gazette 17: 358. 1892. 
[362] 
