In the disjunct portion of its range, Allotropa virgata occurs in 

 harsh, low productivity sites. It grows on dry, acidic, sandy to 

 gravelly, granitic soils which are shallow and well-drained. The 

 plant also seems to require decaying logs or at least a two inch 

 layer of humus (Carver 1991) . Charred wood, fire scars, and a 

 relatively low amount of downed wood indicate fire history, but 

 the frequency and intensity, with the exception of stand- 

 destroying and thus A. virgata destroying blazes, necessary for 

 the health of A. virgata . are not known. Understory vegetation 

 is sparse (canopy cover 0-50%, Carver 1991), repetitive, and of 

 low diversity. The overstory is fairly closed (40-80% canopy 

 cover. Carver 1991) and dominated by lodgepole pine, with Douglas 

 fir as an occasional co-dominant. Stand age varies from around 

 80 years to over 300 years, with an average age of about 200 

 (Lichthardt and Mancuso 1991; Roe 1992). However A. virgata has 

 been observed growing in a "doghair" stand of lodgepole pine in 

 Idaho (Lichthardt and Mancuso 1991) . Allotropa virgata is a 

 component of the subalpine fir/grouse whortleberry or subalpine 

 fir/beargrass habitat types, and subalpine firs when present are 

 usually in the seedling or sapling stage. During the course of 

 this study, two previously unreported species for A. virgata 

 habitat were discovered. Alnus sinuata (Sitka alder) was found 

 at the Gory Creek site on the Beaverhead National Forest, and 

 Juniperus communis (common juniper) was located at the Meyers 

 Creek site on the Deerlodge National Forest. 



The disjunct Northern Rocky Mountain populations of Allotropa 

 virgata are found primarily between elevations of 5000-7800 feet. 

 However one population in Idaho was found near 2300 feet, and at 

 least one plant was seen in Montana around 8000 feet (Carver, 

 pers. comm. , 1992). In the species' main range, the plants are 

 commonly found at lower elevations. Although the species can be 

 found on all aspects, it is generally prefers southerly exposures 

 on lower slopes up to ridgetops. It occurs on almost level 

 ground to moderately steep slopes, although it is perhaps most 

 common on gentle slopes. 



In the past Allotropa virgata has been referred to as a 

 saprophyte. However it is actually a mycotroph, a plant which 

 obtains its sustenance from a fungus associated with its roots. 

 The fungus is attached to a photosynthetic plant which indirectly 

 provides nutrition to the mycotroph via the fungal intermediary. 

 In Oregon the mycorrhizal fungus associated with A. virgata is 

 Rhizopogon vinicolor (Castellano and Trappe 1985) . Whether the 

 same fungus occurs with A. virgata in Montana and Idaho is not 

 known. The photosynthetic species in the chain are most likely 

 lodgepole pine and/or Douglas fir. Because of this co-dependency 

 A. virgata is quite sensitive to loss of these trees whether 

 through timber harvest or stand-replacing fire. However as long 

 as a certain amount of live trees remain, populations of A. 

 virgata can survive. A vigorous A. virgata has been observed 

 within three meters of a clearcut (Carver 1991) , and at least one 



