Halimolobos virgata 

 Twiggy halimolobos 



A. CLASSIFICATION 



1. SCIENTIFIC NAME: Halimolobos virgata (Nutt.) 0. E. Schulz 



2. COMMON NAME: Twiggy halimolobos 



3. FAMILY: Brassicaceae (Mustard Family) 



4. GENUS: Halimolobos (no common name); was originally placed in 

 the genus Arabis . It is closely related to the genus Sisymbrium 

 in having siliques which are terete or very nearly so, wingless 

 seeds, and incumbent cotyledons. It is distinguished in having 

 multi-branched trichomes that make up a canescent pubescence; the 

 siliques are often densely pubescent as well (Rollins 1943) . 



5. SPECIES: H. virgata (Lat. twiggy); closely related to H. mollis , 

 an arctic species. 



B. PRESENT LEGAL OR OTHER FORMAL STATUS 



1. FEDERAL STATUS 



a. U.S. FISH AND WILDLIFE SERVICE: None 



b. U.S. BUREAU OF LAND MANAGEMENT: Watch 



c. U.S. FOREST SERVICE: None 



2. STATE: Prior to this study, Halimolobos virgata was given an 

 "SI" state rank of critically imperiled. From this study and 

 concurrent survey in the Tendoy Mountains (Vanderhorst and Lesica 

 1994) , as well as review subsequent to the Tendoy Mountains 



- report, it is being kept with an "SI" state rank based on five 

 current records. 



It is strictly adventive in one of the five current records for 

 this species, but is otherwise dependent on natural habitat. Its 

 habitat is characterized as "open plains and foothills, sometimes 

 becoming weedy" (Hitchcock et al. 1964) . If there are other 

 sites at which it is restricted to unnatural disturbance 

 settings, then the appropriateness of maintaining it on the state 

 list of species of concern will be re-evaluated. 



The presence of Halimolobos virgata in native prairie habitat of 

 the Sweetgrass Hills, as well as in the biogeographically similar 

 Cypress Hills (Rollins 1943) contributes to a conservative state 

 rank. 



C. DESCRIPTION 



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