EXPLANATION OF PLATES. 



Plate I. Poa tunieri Scril»n. a, empty glumes of 9 spikelet; h, four florets of 



the same; c, empty glumes of ^ spikelet; d, llorets of the same. 

 Plate II. Poa leibergii ScriLn. a, empty glumes; h, spikelet with the empty 

 glumes removed ; the lower figure on the left represents the flower- 

 ing glume expanded. 

 Plate III. Panicum leibergii Scribn. a, spikelet showing first glume; ?>, spike- 

 let seen from the opposite side, showing the second glume ; c, spikelet 

 seen from the side, showing portions of four glumes; d, third glume 

 with its palea; e, fourth glume seen from the back; /, fourth glume 

 and palea. 

 Plate IV. Elymus Itrownii Scribn. & Smith, a, iwrtion of the rachis of the 

 spike, showing two pairs of empty glumes; h, sjiikelet, empty 

 glumes removed. 

 Plate V. Eragrostis obtusiflora Scribn. a, empty glumes of the spikelet; b, 

 spikelet, the lower empty glumes removed; c, flowering glume 

 expanded; d, lateral view of palea; e, portion of the rootstock. 

 Plate VI. Sporobolus plumbeus Hemsl. rt, spikelet; fc, empty glumes; c, flower- 

 ing glume and palea; d, caryopsis. 

 Plate VII. Muhlenbergia flaviseta Scribn. a, empty glumes; ?), flowering glume 

 and palea, a portion of the awn removed; c, second empty glume, 

 expanded. 

 Plate VIII. Leaf structure of Joiivea and of Eragrostis obtusiflora. 



Fig. 1. Poi'tion of a basal section of the leaf of Jourca pilosa; a, h, epidermal 



cells. 

 Fig. 2. Portion of a median section of the leaf of Jo uvea pUosa; a, exodermal 



expansion of an epidermal cell. 

 Fig. 3. Diagram of median section of the leaf of Eragrostis obtusiflora, showing 



conduplicate foi"m. 

 Fig. 4. Diagram of a transverse section of the leuf of Eragrostis obtusiflora, 



showing involute form. 

 Fig. 5. Apical section of the iaaf of Jourea pilosa. 

 Plate IX. Leaf structure of Jourea, Eragrostis obtusiflora, and Distichlis spicata. 

 Fig. 6. Portion of a median section of a leaf of Jourea straminea; b, lateral 



bulliform cells. 

 Fig. 7. Portion of a section of a leaf of Eragrostis obtusiflora. 

 Fig. 8. Portion of a section of a leaf of Distichlis spicata. 

 Fig. 9. Portion of a section of a leaf of Distichlis spicata, bleached, showing 



radial arrangement of cells. 

 Fig. 10. a, portion of longitudinal section of a leaf of Jourea pilosa ; b, isolated, 

 lobed, assimilating cells. 



In figures 1 to 9 inclusive of Plates VIII and IX the lettering is as follows : 

 Transverse sections: M, midnerve; inf ep, inferior epidermis; sup cp, superior 

 epidermis; B, group of bulliform cells; ch, ]iitted chhjrophyll-beariug cells; I, 

 lobed chloro])hyll-bearing cells; cj<, colorless parenchyma; x, xylem; jj/i, phloem; 

 8, sheath of tibro-vascular bundle; st, stoma. 

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