3. SOIL RELATIONSHIPS: Eriogonum la gopus is common on sandy 

 clav soils derived from sandstone and shale and on sandv soil 

 derived from Chugwaier sandstone. It also occurs on sandy soil 

 derived from limestone and calcareous sandstone. It iKcurs most 

 often in shallow or eroding soils. Most of these soils probably have 

 an alkaline reaction and many are probably saline. 



4. REGIONAL CLIMATE: The climate of southern Carbt^n County is 

 semi-arid. Bridger. Montana, just north and west of the Pryor 

 Mountain Desert, receives an average of 12.7 inches annual 

 precipitation, and mean daily temperatures for January and July arc 

 2I.5T and 70.5T, respectively (NOAA I9S2). Ltncll.' Wyoming, on 

 the east side of the Pryor Mountain Desert, receives an average ol 

 7.1 inches precipitation annually. Daily temperatures averagcil 

 I6.8"F in January and 7I.8"F in July (Knight ei al. I9S7). Spring 

 and early summer rainfall accounts for two-thirds of the annual 

 precipitation, the balance coming as smnv (Knight el al. 1987). 



F. POPULATION DEMOGRAPHY AND BIOLOGY 



1. PHENOLOGY: In southern Carbon County. F.riogonum la gopus 

 flowers from mid-June through mid-July. In IWI. a very late \car. 

 flowering did not really begin until early July and probably continued 

 through late July. 



2. POPULATION SIZE AND CONDITION: In southern Carbon 

 County most populations of Eriogonum la gt^pus consist of more than 

 1(XX) plants and iKCupy several to hundreds of acres. Due to the 

 extensive size of most populations, we did not attempt to estimate 

 total population sizes. Estimates for £. lagopus density in 1.2-acrc 

 plots in many of the populations are given in Table I. 



3. REPRODUCTIVE BIOLOGY , 



a. T^TE OF REPRODUCTION: Production of seed is the only 

 known method of reprcxluction in Eriogonum lagopus . 



b. POLLINATION BIOLOGY: The pollinator(s) of Eriogonum 

 la gopus in southern Carbon County are not known. The 

 umbellate inflorescence and small size of individual flowers 

 suggest that E. lagopus may be serviced by generalized 

 pollinators, such as flies and beetles, that crawl over the 

 surface of the inflorescence as in members ol the Apiaceae 

 (Faegri and van der Fiji 1971). it is also quite possible that 



