134 
IOWA ACADEMY OF SCIENCES. 
on either side of the carene, while the number as a whole is 
uniform, forty-one and forty- nine. The edges of the leaves 
are completely filled with stereome (Ste.). The stereome 
occurs only on the lower side of the smaller closed bundles, 
and in sections of this species is not so abundant as in A. pro- 
vincialis. The mesophyll (Mes.) is more abundant in A. nutans 
than in A. provincialis. In shape and size the cells are about the 
same. In this portion we find small intercellular spaces. The 
uncolored parenchyma cells about the carene occur in about 
the same proportion as in A. provincialis. 
ANDROPOGON SCOPARIUS. 
(PI. xiii, Figs. 6 and 8; PI. xv, Fig. 13.) 
In this species the epidermal cells (E. C.) do not differ in 
detail essentially from A. provincialis and A. nutans. They are 
quite variable in size. Cuticle (C.) is well developed. Tri- 
chomes (Tri.) are scattered but conspicuous. 
The bulliform ceils (B. C.) are sufficiently characteristic to 
distinguish it from all other species studied. They occur as an 
almost continual row the entire breadth of the leaf with the 
exception of above secondary bundles, this space is occupied 
by stereome. 
Stereome occurs in groups of from three to eight cells, more 
uniform in size than in the other species studied. The prin- 
cipal distinguishing feature between this and other members of 
the genus studied lies in the continuous row of bulliform cells 
which occurs across the upper portion of the carene (Car.) this, 
in other species, is occupied by sterome. 
The four types of bundles occur in this species as in others 
studied. The carene is bulged below. Stereome (Ste.) is 
abundant. The epidermal cells on the lower surface of the leaf 
below the carene are somewhat irregular with reference to the 
cell wall, the latter is also stratified. 
The uncolored parenchyma occupies the space between the 
bulliform cells and the bundles of the carene, forming more or 
less of a continuous row up to and slightly beyond the first sec- 
ondary bundle, except for such interruptions due to the devel- 
opment of stereome of bundles of third type. Beyond this it 
is confined to from two to six cells above the mesophyll. 
Stereome does not occur above carene as in other species stud- 
ied. Pitted and spiral ducts are large and well developed. 
Leptome (L.) and hadrome (H.) are well developed in this 
species. 
