How To Read The List 



The list is organized alphabetically by scientific name. The ranks in the list are explained below. 

 Heritage Program Ranks 



The international network of Natural Heritage Programs employs a standardized ranking system to denote 

 global (range-wide) and state status (Association for Biodiversity Information 2001 ). Once community 

 types are identified, they are ranked based on their abundance, health and /or level of risk. Ranking helps 

 managers determine which communities or habitat types may be most in need of attention, and can also 

 help focus future surveys or studies to inform management. Ranks are assigned at the global (rangewide) 

 level as well as for Montana. Through our participation in the network of Natural Heritage Programs, we 

 have access to information about the status of communities where they extend beyond Montana's borders. 



Rank Deflnition 



Gl SI Critically imperiled because of extreme rarity and/or other factors making it highly 

 vulnerable to extinction. 



G2 S2I Imperiled because of rarity and/or other factors making it vulnerable to extinction. 



03 S3 Vulnerable because of rarity or restricted range and/or other factors, even though it may 



be abundant at some of its locations. 



04 S4 Apparently secure, though it may be quite rare in parts of its range, especially at the 



periphery. 



05 S5 Demonstrably secure, though it may be quite rare in parts of its range, especially at the 



periphery. 



Possibly imperiled, but status uncer-tain; more information needed. 



Native in nearby states, but in Montana believed to be accidentally introduced, 

 deliberately planted, or escaped from plantings. 



Historical, known only from records over 50 year ago; may be rediscovered. 



Believed to be extinct; historical records only. 



Combination Ranks 



G#0# or S#S# 



Indicates a range of uncertainty about the rarity of the species. 



Sub-rank 



T# Rank of a subspecies or variety; appended to the species' global rank of the full species, e.g. 

 G4T3. 



Qualifiers 



Q Taxonomic questions or problems exist, more information needed; appended to the global rank, 



e.g. G3Q. 



? Denotes uncertainty or for numeric ranks, inexactness. 



