Eriogonum lagopus is capable of self-pollination and 

 produces a proportion of its seed by selfing. 



c. SEED DISPERSAL AND BIOLOGY: The fruit of 

 Eriogonum lagopus is a small hard achene. These achenes 

 may be dispersed by seed-gathering insects such as ants. In 

 some cases, the dried perianth may remain around the 

 achene and act as wings, similar to the fruits of some species 

 of Rumex . In this case, the seeds would be dispersed by wind 

 (van der Pijl 1982). 



d. SEEDLING BIOLOGY: Eriogonum lagopus occurs in a vcia 

 arid region. Recruitment may be limited to years with 

 prolonged periods of above-average precipitation. Few 

 seedlings were observed in 1991. 



G. ECOLOGY 



1. BIOLOGICAL INTERACTIONS: 



a. COMPETITION: Eriogonum lag(^pus occurs oni\ in spaiNc 

 vegetation in very arid environments. Although plants in 

 these sites are widely spaced, competition for water may be 

 intense. It is unlikely that competition for nutrients or light is 

 important. 



Halogeton glomeratus is an exotic annual that has become 

 common at the north end of the Bighorn Basin. Hak)gcton 

 glomeratus increases the salinity of the soil which favors its 

 own seedlings (Sauer 1988). It is possible that as this invasiw 

 species becomes more common in arid communities, ii could 

 limit recruitment of native perennials in much the same way 

 that Bromus tectorum competes with native vegetation in the 

 steppes west of the Continental Divide (Mack 1981). 



b. HERBIVORY: We observed no evidence of herbivon.' from 

 insects, wildlife or livestock. 



2. HYBRIDIZATION: Hybridization among the perennial species of 

 Eriogonum is common (Welsh et al. 1987). Two closely related 

 species of Eriogonum co-occur with E. lagopus in southern Carbon 

 County: E. paucitlorum and E. mancum . E, paucillorum is one of 

 the putative parent species of E. lagopus . and backcrossing is not 

 unexpected. We also obser\ed plants that appeared intermediate 



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