Table 1. Target list of Montana plant species of special concern in the study area 



'Species and communities are evaluated and ranked by the Heritage Program on the basis of their global (rangewide) 

 status and their state (statewide) status according to a standardized procedure, using the following set of values and 

 accompanying deftnnitions. 

 Rank Definition 



Critically imperiled because of extreme rarity (5 or fewer occurrences, or very few remaining individuals) or 



because of extinction-prone factors. 



Imperiled because of rarity (6-20 occurrences), or because of other factors making it demonstrably vulnerable to 



extinction. 



Vulnerable because of rarity (21-100 occurrences) or found in a restricted range. 



Apparently secure, though it may be quite rare in parts of its range, especially at the periphery. 



Demonstrably secure, though it may be quite rare in parts of its range. 



Known only from historic records; possibly extirpated but concerted searches have not been conducted 



