INTRODUCTION 



This report describes the establishment of a monitoring 

 program for Agastache cusickii in the Tendoy Mountains of 

 southwestern Montana. The population which is being monitored 

 is located on a steep limestone talus slope above Big Sheep 

 Creek in Beaverhead County. This occurrence, the only known 

 for this species in Montana, was only recently discovered 

 (Lesica et al. 1986) . Despite further intense searching in 

 the vicinity by Peter Lesica and myself during the svimmer of 

 1993 no other locations have been found (Vanderhorst and 

 Lesica 1994) . Although the U. S. Fish and Wildlife Service 

 (1990) classified Agastache cusickii as 3C ("not subject to 

 any identifiable threat") , the Montana Natural Heritage 

 Program (Heidel and Poole 1993) classifies the species as SI 

 ("critically imperiled because of extreme rarity") in Montana. 



Agastache cusickii (Cusick's giant-hyssop or horse-mint) 

 is a member of the Lamiaceae (the mint family) . It can be 

 distinguished from the very common and widespread Agastache 

 urticifolia by its dwarf habit and smaller leaves. Besides 

 its apparently disjunct Montana occurrence, Agastache cusickii 

 is found at scattered locations in the mountains of 

 southeastern Oregon, northern and eastern Nevada, and central 

 Idaho, in dry, rocky places, often on talus (Cronquist et al. 

 1984) . 



The talus where the plants are found in the Tendoy 

 Mountains is located adjacent to a major gravel road, and in 

 the past the site was quarried for road construction material. 

 Removal of this material undoubtedly directly reduced the 

 population area and may have also affected upslope habitat by 

 reducing lateral support for the talus. In addition to 

 Agastache cusickii, 3 other Montana Plant Species of Special 

 Concern found on these slopes are Hutchinsia procumhens, 

 Mimulus suksdorfii, and Phacelia incana. Although authorized 

 quarrying seems to have been suspended in recent years, the 

 ELM wished to establish a monitoring program to document 

 habitat trend and any threats due to unauthorized quarrying. 

 A monitoring system was established in the summer of 1993 

 through a challenge cost-share between BLM and the Montana 

 Natural Heritage Program at the site. 



The primary purpose of monitoring this site is to detect 

 further degradation of habitat. This contrasts with 

 monitoring of other populations of sensitive plants where the 

 primary goal is to study the natural history traits of the 

 species, population trends or management responses. The major 

 threat to Agastache cusickii here is not its intrinsic 

 reproductive capacity, but rather disturbance of habitat by 

 people. A secondary benefit of this program will be to 

 determine the species ability to recolonize previously 

 disturbed habitat. 



