146 
IOWA ACADEMY OP SCIENCES. 
one-fourth or one- third the width of section; no colorless paren- 
chyma. E, pursbii. 
b. Carene enlarged preceptibly, especially on inferior side, easily dis- 
tinguishable; trichomes equal in length to one-tenth or one-sixth 
of the section; colorless parenchyma present. 
1. Leaf small; upper surface presents a fluted appearance in section; 
carene and vein 2 strongly developed, the latter on superior side 
especially; chlorophyll-bearing parenchyma sheath in secondary 
bundles (vein 3) subpyramidal in outline; cells of same subcircular 
and the inferior cells much smaller than the rest. E. frankii 
2. Leaf large, fluted but little on superior surface; carene enlarged 
‘ on inferior side only; vein 2 not enlarged; chlorophyll-bearing 
parenchyma sheath circular in outline; cells subcircular, equal in 
size. 
t Colorless parenchyma, fifteen to twenty cells, interrupting the mes- 
tome and chlorophyll- bearing parenchyma sheaths above the 
bundles in the carene. E mexicana. 
ft Colorless parenchyma, three to five cells, interrupting the mestome 
sheath above the bundle in the carene; small button-shaped scent 
glands, numerous on the margins of all leaves and on the median 
nerve of both sterile and flowering glumes. E. major. 
EXPLANATION OP PLATES. 
All the figures were drawn from nature by the author and prepared for the 
engraver by Miss Charlotte M. King, artist for the bov.anical department. 
The abreviations used are: 0., cuticle; E. 0 , epidermal cells: Tr., trichome; Sto , 
stoma; B., bulliform cells; Ste., stereome; Mes., mesophyll; M. S., mestome sheath; 0. 
P., colorless parenchyma; O. B. P., chlorophyll-bearing parenchyma; H., hadrome; L., 
leptome; Sup., superior; inf., inferior; Oar., carene; Vein 2, vein next smaller than 
carene; Vein 3, smallest veins. 
PLA.TE xvi. All drawings on this plate were made with camera, and drawn to the 
same scale. Fig. 1. E. reptans, carene to margin: Fig. 3, E. pursJiii, carene to second 
vein 2; Fig. 3, E. mexicana, carene to first vein 3; Pig. 4, E. major, carene to first vein 3; 
Pig. 5, E. pectinacea, carene to first vein 3; Pig. 3, E. /mn/cn, carene to first vein 3. 
Mesophyll and epidermis colored black. 
PiiATB xvil. All drawings on this plate, except Fig. 13a, made with a one-sixth 
inch objective. Fig 13a, drawn with a one-tenth inch oil immersion objective. All 
reduced one-half. Pig. 7, E. mexicana, carene and vein 3, primary and secondary types, 
respectively; Fig. 8, E. mexicana, vein 3, primary type; Fig. 9, E. pectinacea, carene, 
"intermediate type, and vein 3, secondary type; Pig. 10, E. pectinacea vein 3, interme- 
diate type; Fig. 11, E. frankii, vein 3, primary type; Pig 13, E. frankii, carene, interme- 
diate type, and vein 3, secondary type; Pig. 13a, E. frankii, inferior part of carene; X, 
normal stereome; Z, modified stereome. 
Plate xviii. All drawings on this plate made with a one- sixth inch objective; all 
reduced one-half. Fig. 13, E. major, vein 3, secondary type, vein 3, intermediate type; 
Fig 14, E. major, carene, intermediate type; Pig. 15, E. purshii, vein 3, intermediate 
type; Fig. 16, E. purshii, careae, intermediate type and vein 3, secondary type; Pig. 17, 
E. reptans, veins 3 and 3, intermediate type; Fig. 18, E. reptans, carene and vein 3, 
intermediate type; Pig. 19. E. major, scent gland, superficial view; Fig. 30, two scent 
glands on leaf margin, E. major. 
