b. POLLINATION BIOLOGY: Halimolobos virqata has weakly-developed 

 nectar glands, adapted for insect pollination. No pollinator 

 visits were observed. The most likely insect visitors in early 

 spring are bees (Hymenoptera) and flies (Diptera) . 



c. SEED DISPERSAL AND BIOLOGY: The siliques dehisce along the 

 length of valves on either side of the fruit. The small, 

 lightweight seeds are not known to have any dispersal adaptation 

 and might be expected to fall around the base of the parent 

 plant. 



G. POPULATION ECOLOGY 



1. BIOLOGICAL INTERACTIONS 



a. COMPETITION: The coarse, droughty soils overlying limestone or 

 sandstone on which it grows may reflect poor competitiveness. 



b. HERBIVORY: Many inf loresences of Halimolobos virqata were grazed 

 or browsed in the Sweetgrass Hills site northwest of Black Jack 

 Butte, which was opened for early-season livestock grazing in 

 1993. Inf loresences were eaten at the Sweetgrass Hills site 

 southeast of Black Jack Butte in a pasture which had not been 

 open to livestock grazing at the time of visit. They are 

 apparently among the first palatable forbs to bolt in their 

 habitat. These observations suggest that they are likely to be 

 grazed by cattle early in the growing season. Grazed plants 

 produced multi-branched inf loresences which still flowered and 

 set seed in the moist 1993 growing season. 



H. LAND OWNERSHIP Three of the five known locations for this 

 species are on lands administered by the BLH. 



EG no. Land ownership 

 ~ 001 Sweetgrass Hills - Dohrs Creek; BLM-Lewistown District 

 on recently-acquired tract 



002 Sweetgrass Hills - Sage Creek; private 



003 Tendoy Mts. - Pileup Canyon; BLM-Butte District 



004 Tendoy Mts. - Limekiln Canyon; BLM-Butte District 



005 East Pioneer Mts.; Blacktail Game Management Area 

 of Montana Fish, Wildlife and Parks Dept. 



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