1914] VESTAL— PRAIRIE VEGETATION 399 



southern part of the plains region, and is not common in the foot- 

 hills or even in the mesa- terrace, Artemisia frigida Willd. ranges 

 far to the north, and forms an important primitive growth in the 

 mountains to as high as 10,000 feet. The Artemisia frigida con- 

 socies, therefore, is the important growth of the mountain-front, 

 being quite frequent on talus slopes and gravel slides of the foot- 

 hills. Bouteloua hirsuta Lag. is often associated with Artemisia; 

 this growth may represent a separate association. 



The Gutierrezia- Artemisia growth in the plains of the region 

 contains Eriogonum effusum Nutt. and Grindelia squarrosa (Pursh) 

 Dunal, sometimes abundantly. There are indications that rela- 

 tive abundance of Gutierrezia and Artemisia is materially influenced 

 by grazing animals, Gutierrezia being apparently more resistant. 



University of Chicago 



LITERATURE CITED 



1. Bray, W. L., Distribution and adaptation of the vegetation of Texas. 

 Bull. Univ. Tex. no. 82. pp. 108. 1906. 



2. Brendel, F., Flora Peoriana. The vegetation in the climate of middle 



Illinois. Peoria. 1887. 

 3- Dodds, G. S., Geology and physiography of the mesas near Boulder. 



Univ. Colo. Studies 6:11-19. 1908. 



4. Fenneman, N. M., Geology of the Boulder district, Colorado. U.S. Geol. 



Surv. Bull. no. 265. pp. 101. 1905. 



5. Gleason, H. A., The vegetation of the inland sand deposits of Illinois. 

 Bull. 111. State Lab. Nat. Hist. 9:23-174. 1910. 



6. Hall, E., Notes on some features of the flora of eastern Kansas. Trans. 



Amer. Acad. 50:29-35. 1870. 



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Vegetation der Erde 13: pp. 790. 191 1. 



8. Harvey, L. H., Floral succession in the prairie-grass formation of south- 

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9. Hitchcock, A. S., Ecological plant geography of Kansas. Trans. Acad. 



Sci. St. Louis 8:55-69. 1898. 



10. Johnson, W. D., The high plains and their utilization. Ann. Repts. U.S. 



Geol. Surv. 21, part 4. pp. 599-74 1 ; 22 » P art 4- PP- 631-669. 1900, 1901. 



11. Lee, W. T., The origin of the debris-covered mesas of Boulder, Colorado. 



Jour. Geol. 8:504-511. 1900. 



12. Pound, R., and Clements, F. E., The vegetation regions of the prairie 



province. Bot. Gaz. 25:381-394. 1898. 



