tridentata or Cercocarpus ledifolius with Agropyron spicatum. 

 Most of these habitats are subject to livestock grazing. 



D. POPULATION BIOLOGY 



Estimated population numbers range from 100 to 10,000 

 individuals. Thistles, in general, were not yet blooming in 

 June, but were by late July. Although its habitats are often 

 grazed, no predation of C. subniveum was observed. 



E. MANAGEMENT CONSIDERATIONS 



The species is widespread in southern Beaverhead and Madison 

 counties, with some extensive populations. Furthermore, 

 thistles are often ignored or avoided by botanists or plant 

 collectors; thus, this species may be more common than is 

 currently known. We recommend that C. subniveum be dropped 

 from further BLM consideration and from state tracking. 



Delphinium bicolor Nutt. ssp. noviim 



New subspecies of Montana larkspur 



A. DESCRIPTION 



1. General description: This larkspur (Ranunculaceae) has been 

 identified in the past as D. andersonii or D. geyeri . 

 Specimens were shown to Stan Welsh (Brigham Young University, 

 Provo, Utah) who suggested that description as a variety under 

 D. geyeri was warranted, but these plants may be more closely 

 related to D. bicolor. A specialist in the genus, Michael 

 Warnock (Sam Houston State University, Huntsville, Texas) 

 plans to name this taxon as a subspecies of D. bicolor. The 

 plants are relatively short, with deep, strong roots. The 

 deeply palmately cleft leaves are mostly basal and are nearly 

 hairless to fairly densely hairy. The large, showy blue 

 flowers are borne on long, spreading pedicels and are 

 irregular with the large sepals flaring in front and the upper 

 one producing a prominent spur in back. The petals are 

 smaller, the upper are blue tipped (sometimes solid white) 

 without pigmented veins. There are usually 3 pistils, which 

 develop into follicles. A slide (7) of the plant is attached 

 in Appendix E. 



2. Technical description: not yet available. 



3. Diagnostic characters: These plants are geographically 

 sympatric to D. bicolor, which they resemble. The key 

 distinction in the field is the upper petals, which are blue 

 tipped or solid white, in contrast to the blue veined petals 

 of D. bicolor. In addition, the flowers are somewhat larger, 

 the sepals are deeper blue and the lower petals are more 

 deeply cleft (Warnock, pers. commun.). There also seems to be 



20 



