10 



both species of Typha in the marshes of varying salinity formed 

 by the emptying of the relatively pure waters of Bear River into 

 the highly concentrated waters of the Great Salt Lake. During 

 the summer of 1923, I found T. angustifolia growing under con- 

 ditions which make its occurrence in Utah of considerable biol- 

 ogical interest. 



The station in question represents a small area only a few 

 square yards in extent in the marshes which are fed by the Fume- 

 role Butte hot springs near the northern end of the Sevier desert.* 



These hot springs, with a temperature of 110-178° F., are 

 rather highly mineralized, having an osmotic concentration (de- 

 termined cryoscopically) of 2.15 to 2.40 atmospheres,! and have 

 built up considerable mounds of deposits, below which are densely 

 vegetated sloughs. The vegetation of the low ridges between 

 the sloughs is typical of the surrounding highly saline deserts, 

 with the stem succulent Allenrolfea occidentalis {S. Wats.)Kuntze, 

 having an osmotic concentration of its tissue fluids of forty at- 

 mospheres or more, J a conspicuous species. 



On some very recent deposits from the springs Sesuvium 

 sessile Fers., with an osmotic concentration of the tissue fluids 

 of its succulent leaves of about twenty-five atmospheres, is the 

 only species. A much dwarfed sunflower, presumably Helianthus 

 aridus R^'db. (fourteen to eighteen atmospheres) is represented 

 by a few individuals on the banks of the streamlets of hot water. 

 Glaux maritima L. (with an osmotic concentration of twenty 

 atmospheres) was taken near the margins of the marshes. Crepis 

 glauca (Nutt.) Torr. and Gray, with succulent leaves (about 

 eighteen atmospheres) and Aster pauciflorus Nutt., are also 

 found. 



*The position of this group of springs is indicated on the map of the old 

 river bed which formed the connection between the Sevier and the Great 

 Salt Lake Desert Sections of the main lake. See G. K. Gilbert, Lake 

 Bonneville, PI. 31, pp. 332-335- 1890. 



fThese are the values determined from the water emerging from the springs 

 or from pools near the springs. After exposure to evaporation in the lower 

 portion of the marshes the concentration of the soil solution is undoubtedly 

 very much higher. 



tOsmotic concentrations of the leaf tissue fluids, or of the stem-tissue fluids 

 in the c^e of leafless forms, has been determined by a technique developed 

 and used for this purpose in a number of investigations published during the 

 past several years. The results are given in round numbers of atmospheres. 



