ILLUSTRATIONS. 



PLATES. 



Facing page. 



Plate 67. Habitat of Bouteloua spp. in the Tucson Mountains, Arizona 343 



68. A. Closely grazed Bouteloua region in southern Arizona. B. Habitat 



of tall-growing species of Bouteloua in southern Arizona 345 



69. A. Bouteloua curtipendula (Michx.) Torr. in cultivation. B. Bou- 



teloua gracilis (H. B. K.) Lag. in cultivation 345 



70. A. General view of a good Bouteloua region. B. Spring view of a 



Bouteloua region closely grazed 346 



71. A. Typical view in a Bouteloua region showing a variety of species. 



B. Bouteloua region with a different soil and different species. . 346 



72. A. Large native crop of Bouteloua gracilis (H. B. K.) Lag. B. Bou- 



teloua gracilis on the Mexican border of Arizona 377 



73. A. Large plant of Bouteloua parryi (Fourn.) Griffiths. B. Bou- 



teloua barbata Lag 382 



74. A. Bouteloua trinii (Fourn.) Griffiths. B. Bouteloua eriopoda Torr . 388 



75. A. Isolated plant of Bouteloua rothrochii Vasey. B. Dense growth 



of Bouteloua rothrochii 392 



76. Habitat of Bouteloua harioinshii (Fourn.) Griffiths, B. trinii (Fourn.) 



Griffiths, and B. stolonifera Scribn 394 



77. A. Large plant of Bouteloua aristidoides (H. B. K.) Griseb. B. 



Same species on desert mesas 397 



78. Bouteloua eludens Griffiths 402 



79. Bouteloua eludens Griffiths 402 



80. A. Bouteloua eludens Griffiths. B. Bouteloua texana S. Wats 402 



81. Bouteloua radicosa (Fourn. ) Griffiths 412 



82. A. Bouteloua jiliformis (Fourn.) Griffiths. B. Bouteloua curti- 



pendula (Michx. ) Torr 413 



83. Bouteloua jiliformis (Fourn.) Griffiths 413 



TEXT FIGURES. 



Page. 



Figure 19. Triaena juncea 355 



20. Pentarrhaphis scabra 356 



21. Pentarrhaphis polymorpha 357 



22. Cathestecum prostratum 358 



23. Cathestecum prostratum 359 



24. Cathestecum multifidum 360 



25. Cathestecum erectum 361 



26. Cathestecum stoloniferum 363 



27. Bouteloua procumbens 366 



28. Bouteloua simplex 367 



29. Bouteloua simplex 367 



30. Bouteloua stolonifera 368 



31. Bouteloua scorpioides 370 



32. Bouteloua scorpioides 370 



33. Bouteloua hirticulmis - 371 



vn 



