fecunda are also discussed in Hamilton and 

 Mitchell-Olds (1989) . 



Transects were also established in 1989 at two 

 locations on the Beaverhead National Forest 

 (Slides, p. 10) . Preliminary data indicate that 

 fecundity, measured as number of plants fruiting, 

 percent of plants fruiting, number of fruits per 

 fruiting plant, and number of fruits per 

 inflorescence, was lower (in 1989) at Lime Gulch 

 (012) than at Canyon Creek (013). However, the 

 Lime Gulch population is approximately 1,000 feet 

 lower in elevation than Canyon Creek (Oil) , and is 

 located on the lower eastern flanks of the Pioneer 

 Mountains in the rain shadow of some of the 

 highest peaks of the range. Thus, it is likely to 

 receive substantially less precipitation and have 

 warmer temperatures than the Canyon Creek 

 population. This in turn influences the phenology 

 and possibly the fecundity of the populations. 

 The data indicate that there needs to be at least 

 a one to two week delay in reading the Canyon 

 Creek transects, in order to obtain data 

 comparable to Lime Gulch. The report on this study 

 is found in Appendix A, p. 45. 



REPRODUCTIVE BIOLOGY 



a. TYPE OF REPRODUCTION: Arabis fecunda is a 

 perennial species that reproduces only by 

 seed. Individual plants continue to grow 

 larger each year through branching and 

 enlargement of the caudex. Early bloom dates 

 may indicate that A. fecunda is facultatively 

 autogamous (Lesica 1985) . 



b. POLLINATION BIOLOGY: The mechanisms of 

 pollination are unknown for this species; 

 however, it may be through selfing and/or by 

 insects. 



c. SEED DISPERSAL AND BIOLOGY: Flowers and 

 fruits mature acropetally, developing from 

 the base of the plant to the apex. The often 

 numerous fruits mature quite quickly. 

 Although not directly observed, dispersal of 

 seed is probably similar to that of other 

 species of Arabis . Valves of the siliques 

 open from the tip downwards, which expose the 

 seeds that then drop, or are shaken to the 

 ground (Lesica 1985) . 



