76 



Stepbanomeria spinosa (Nutt.) S. Tomb 

 SPINY SKELETONWEED 

 Aster Family (Asteraceae) 



CONSERVATION STATUS: 



U.S. Fish and Wildlife Service: None. 



Montana Bureau of Land Management: This species was on the watch Hst distributed 

 for review by the BLM in Montana in 1995. 



Montana Natural Heritage Program rank: G4 SI. 



DESCRIPTION: Multi-steninied perennial. 1.5-8 dm (6-32.5 in.) tall, with spreading, spine- 

 tipped branches from a taproot and branching caudex, with tufts of pale or brownish wool at the 

 base. Leaves all cauline, the lower linear, entire, 3 cm (1 1/4 in.) long or less, the others reduced 

 and scale-like. Heads are numerous, erect, pink or lavender to red-purple; seldom white (Figure 

 32). Involucre is 7-13 mm (3/8-1 1/16 in.) high with graduated bracts and well-developed outer 

 bracts. The seed has numerous bristles (pappus) 7-9 mm (3/8-1/2 in) long that have downward 

 pointed sidebranch bristles. 



The flower resembles that of other Stepbanomeria and Lygodesmia species in the state, but the 

 conspicuously spine-tipped branches readily distinguish it (Appendix D-25). 



GEOGRAPHICAL DISTRIBUTION 



Global distribution: Widespread in the Great Basin, west to southern California, 

 extending north locally to southern British Columbia and southwestern Montana. 



Montana distribution: This species has been documented six times in the state (Figure 

 33). Five of the six records are from the upper Madison River valley centered in the 

 study area. It is not known whether the historic records from the Ennis area and the 

 Moose Creek Canyon area are extant. The sixth record is based on a 1952 specimen 

 collected in the Centennial Valley. 



Upper Madison Valley distribution: The three recent records span ca. 10 discontinuous 

 miles of valley. The historic Moose Creek record is ca. 3 miles southeast, and the historic 

 Ennis record is 15-20 miles north. The potential for habitat on private land or state land 

 has not been evaluated. The three study area occurrences may represent the only ones for 

 this species in Montana on public land (Figure 23). 



