IOWA ACADEMY OP SCIENCES. 
119 
A STUDY OP THE LEAP ANATOMY OP SOME SPE- 
CIES OP THE GENUS BROMUS. 
EMMA SIRRINE. 
The species of genus Bromus are sometimes difficult to dif- 
ferentiate; hence, a study of the leaf anatomy was undertaken 
with a view towards a help in differentiation. 
BROMUS ASPERT.^ 
(PI. V. Fig. 5; PI. vii, Fig. 8.) 
Epidermis . — The cuticle in this species is quite thick. The 
epidermal cells are large, but are smaller and thicker walled 
above and beneath the primary mestome bundles than else- 
where. Stomata frequently occur on both surfaces. The 
upper and lower surfaces of leaf, as well as edges, are provided 
with trichomes, sometimes in the form of small conical pro- 
jections. 
Bulliform --These occur on superior surface, and vary in 
number from three to five, and are not as thick walled as the 
epidermal cells. They occur between the mestome bundles, 
but this arrangement is not uniform, that is, they are not pres- 
ent between all mestome bundles. 
Mestome bundles. — Twenty-nine mestome bundles occur across 
middle portion of leaf. The bundles are of three types: 
Pirst, the primary type numbers eleven bundles. These open 
on both superior and inferior surfaces of leaf, i. e . , the leptome 
and hadrome are in direct contact with the stereome or sep- 
arated from it only by colorless parenchyma cells; they vary in 
size (from the midrib to the margins of leaf); the one of the 
midrib is the largest. Bundles of the secondary type number 
seventeen. These are entirely closed, i. e . , chlorophyll bearing 
*This was determined later as Bromus patulus. M. & K., by F. Lamson-Scribner. 
There is an apparent repetition in papers by Miss Sirrine and Miss Pammel, in fact 
the same species were studied. They appeared distinct, but Professor Lamson-Scribner 
determined them as above. L. H. Pammel. 
