IOWA ACADEMY OP SCIENCES. 
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characters. The opened and closed bundles are variable in 
number and difficult to distinguish, as many of the smaller mes- 
tome bundles are very small and close together. 
These species can be distinguised by the following key: 
Bulliform cells in groups of two to four, occasional short tri- 
chomes. A. provincialis, 
Bulliform cells narrow and long, two to five in number, in 
some cases decidedly unequal, short trichomes very numerous. 
A. nutans. 
Bulliform cells three to eight, uniform in size, forming an 
almost continuous row, also above the carene, trichomes con- 
spicuous. A. scoparius. 
Bulliform cells vary in number from two to eight, in definite 
groups, gradually merge into the epidermal cells; smooth. 
A. sorghum. 
Bulliform cells vary in number from two to four, grandualiy 
blending into the epidermal cells. Trichomes few and small 
near carene. A. sorghum, var. Halepense. 
CONCLUSION. 
In conclusion it may be said that each species of the genus 
presented here has individual peculiarities which are strong 
enough to distinguish it from other species of the genus. I 
believe also that a study of the anatomical characters offered in 
grasses will show characters enough to distinguish genera and, 
in many cases, species and even varieties, as for example, in A. 
sorghum and A. sorghum, var. Halepense. By these studies one 
may receive material aid in the classification and the determina- 
tion of many grasses. 
Thanks are due to Mr. Barnes of Blue Grass, who kindly 
sent the leaves of A. sorghum, var. Halepense. 
EXPLANATION OF PLATES, 
The same letter is used for the same character in all of the figures, 0., cuticle; 
E., epidermis; E. O., epidermal cells; Sto , stomata; Tri., trichome; 0. P., conical pro- 
jections; B. C., bulliform cells; Unc. Par., uncolored parenchyma; 0. B. P., chlorophyll- 
bearing parenchyma; Mes., mesophyll ; Ste., stereome; M , mestome; Oar., carene; H., 
hadrome; L , leptome. 
The figures are all drawn with camera to the same scale. Low power with one half 
inch Beck objective; detailed drawings with one-sixth inch Beck objective. 
Figs. 1-9 are reduced three times; Figs. 10-15 not reduced. 
Plate xii. Figs 1 and 5, Andropogon nutans; Figs. 3, 3 and 4, Andropogon pro- 
vincialis, 
Plate xiii. Figs 6 and 8, Andropogon scoparius; Fig. 7, Andropogon sorghum. Fig. 
9, A. sorghum, var. Halepense. 
Plate xiv. Fig. 10, A. sorghum; Fig. 11, A. sorghum, var. Halepense; Fig. 13, A 
provincialis. 
Plate xv, Fig. 13, A. scoparius; Figs. 14 and 15, A. nutans. 
