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alternately on opposite sides of the axis, one above the other, with a 
pair of empty or outer glumes at the base of the cluster. Such may be 
seen in the blue grass (Poa pratensis), fescue grass (Festuca) and many 
others. 
There are innumerable modifications of these floral organs, and upon 
the differences which exist in them the distinctions of genera and species 
are based. In some cases the glumes are entire in outline, in some they 
are toothed and lobed, and sometimes running out into a slender point 
called an awn, sometimes with a bristle or awn on the back, ete. They — 
also vary in size from the twentieth part of an inch to an a or more ~ 
in length. 
PLATE 1. 
Fig. 1. 1, fibrous roots; 4, culm; 5, node; 6, leaf. 
2. 2, rhizoma; 4, culm; 6, blade of leaf; 7, ligule; 9, scales of the rhizoma. 
3. 1, root fibers; 3, bulbous base of culm; 4, culm; 5, sheath; 6, blade. 
4, 2, scaly rhizomas; 4, node; 6, blade; 7, ligule; 9, scales of the rhizoma. 
5. 1, fibrous roots; 2, creeping rhizoma; 4, culm; 5, sheath; 6, blade; 7, enlm; 
8, nodes. 
PLATE 2. 
The numbers in each of the figures are as follows: 1, sheath; 2, blade; 3, culm; 4, 
node, or joint; 5, ligule. 
The ligule is best shown in the lower right-hand figure. 
PLATE 3. 
Fic, 1. A dense spike (Alopecurus pratensis). 
. An elongated, one-sided spike (Paspalum dilatatum). 
. Spike (Hordeum pratense). 
. Spike (Agropyrum repens). 
. Spike (Elymus condensatus). 
Spike (Bouteloua polystachya). 
. Spike (Boutelona oligostachya). 
. Panicle (Panicum Crus-galli). 
. Panicle (Agrostis exarata). 
. Panicle (Keleria cristata). 
11. Panicle (Distichlis maritima). 
12. Panicle (Bromus secalinus). 
13. Panicle (Hierochloa borealis). 
14. Panicle (Poa pratensis). 
15. Panicle (Dactylis glomerata). 
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PLATE 4. 
Fic. 1. Two spikelets, one closed, one opened, of Agrostis vulgaris. 
. Two spikelets, one peat one opened, of Agrostis exarata. 
. Two spikelets, one closed, one opened, of Sporobolus Indicus. 
. An opened spikelet of Calamagrostis Canadensis. 
. Two spikelets, one closed, one opened, of Phleum pratense. 
. Two spikelets, one closed, one opened, of Muhlenbergia diffusa. 
. Two spikelets, one closed, one opened, of Paspalum dilatatum. 
. Two spikelets, one closed, one opened, of Paspalum leve. 
. A spikelet of Aristida purpurea. 
10. Two spikelets, one closed, one opened, of Setaria setosa. 
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