177. Selander, S., "Floristic Phytogeography of Southwestern Lule Lappmark 



(Swedish Lapland)," Acta Geog. Suecica, 27, 1-200 (1950). 



178. Shreve, E.B., "Seasonal Changes in the Water Relations of Desert 



Plants," Ecolog}', 4, 266-292 (1923). 



179. Shreve, F., "Vegetation of the Sonoran Desert," Carnegie Inst. Wash. 



Pubi, No. 591, 1951. 



180. Silliman, F.E. and Leisner, R.S., "An Analysis of a Colony of Hybrid 



Oaks," Amer. Jour. Botany, 45, 730-736 (1958). 

 180A. Sorensen, Th., "A Method of Establishing Groups of Equal Amplitude 

 in Plant Sociolog)' Based on Similarity of Species Content," Kgl. Danske 

 Videnskab. Selskab Biol. Sknfter, J5, No. 4, 1-34 (1948). 



181. Sprague, V.G. and Garber, R.J., "Effect of Time and Height of Cutting 



and Nitrogen Fertilization on the Persistence of the Legume and Pro- 

 duction of Orchardgrass-Ladino and Bromegrass-Ladino Associations," 

 Agron. Jour., 42, 586-593 (1950). 



182. Stebbins, G.L., "Species Hybrids in Grasses," Proc. Internat. Grassl. Cong., I, 



247-253, Pennsylvania State College, 1952. 



183. Stebbins, G.L., "Cytogenetics and Evolution of the Grass Family/' Amer. 



Jour. Botany, 43, 890-905 (1956). 



184. Steere, W.C., "The Cryptogamic Flora of the Arctic: V. Bryophytes," 



Botan. Rev., 20, 425-450 (1954). 



185. Stewart, G., Cottam, W.P., and Hutchings, S.S., "Influence of Unrestricted 



Grazing on Northern Salt Desert Plant Associations in Western Utah," 

 Jour. Agr. Res., 60, 289-316 (1940). 



186. Stickler, F.C. and Johnson, LJ., "Dry Matter and Nitrogen Production of 



Legumes and Legume Associations in the Fall of the Seeding Year," 

 Agron. Jour., 51, 135-137 (1959). 



187. Summerhayes, V.S. and Elton, C.S., "Further Contributions to the Ecology 



of Spitsbergen," Jour. EcoL, 16, 193-268 (1928). 



188. Sylven, N., "The Influence of Climatic Conditions on Type Composition," 



Imp. Bur. Plant Genet., Herb. Plants Bull., No. 21, 1-8 (1937). 



189. Tansley, A.G., "The Use and Abuse of Vegetational Concepts and Terms," 



Ecology, 16, 284-307 (1935). 



190. Tansley, A.G., "The British Islands and Their Vegetation," 2 Vols., Cam- 



bridge University Press, Cambridge, 1949. 



191. Tedrow, J.C.F. and Cantlon, J.E., "Concepts of Soil Formation and 



Classification in Arctic Regions," Arctic, 11, 166-179 (1958). 



192. Thornbury, W.D., "Principles of Geomorphology," John Wiley & Sons, 



Inc., New York, N.Y., 1954. 



193. Timmons, F.L., "The Rise and Decline of Cactus in Kansas," Biennial 



Rept. Kansas State Board Agr., 33, 37-46 (1941-1942). 



194. Tisdale, E.W., "The Grasslands of the Southern Interior of British Colum- 



bia, Ecology, 28, 346-382 (1947). 

 195. Tiixen, R., "Grundrisz einer Systematik der Nitrophilen Unkrautgesell- 

 schaften in der Eurosibirischen Region Europas," Mitteil. Florist-Sozwlog. 

 Arbeitsgemeinschafl., 2 (N. F.), 94-175 (1950). 



BibliograpHy * 201 



