sites for any of these sensitive orchids should be considered potential habitat for the 

 others. Other common associated forbs are Clintonia uniflora . Cornus canadensis . 

 Petasites sagitata . Rubus pubescens . and species of Viola . Graminoid cover is 

 predominantly by small sedges such as Carex capillaris . G disperma . and C. leptalea . 

 The most common associated ferns are horsetails ( Equisetum arvense . R fluviatale . R 

 hymale . and JL scirpoides ). Ground cover by mosses in these habitats is usually very 

 high. 



ECODATA plots were sampled at two sites with Cypriedium passerinum . at Brimstone 

 Creek (025) and at Rattlebone Lake (020). This data is provided in Appendix B, and 

 includes complete lists of vascular plant species in the plots and their aerial coverage. 

 Additional associated plant species are listed in the general site description fields of the 

 Element Occurrence Records in Appendix A. Photographic slides of the vegetation at 

 three sites are provided in Appendix C. 



2. Topography: On the KNF. all occurrences of Cypripedium passerinum are at relatively 

 low elevations in glaciated valley bottoms, along low gradient streams or lakeshores in 

 the Rocky Mountain Trench. Elevations range from 3,280 to 3,800 feet. The sites are all 

 nearly level and have various aspects. At wet sites the plants grow on hummocks above 

 the water table. 



3. Soil relationships: Correll (1950) states that the species "grows in both circumneutral 

 limestone gravels and moderately acid coniferous humus." In Montana, a calcareous 

 parent material is often reported, and on the KNF most of the sites have soils with a high 

 content of reprecipitated calcium. Four of the six known occurrences are on landtype 325 

 (Kuennen and Gerhardt 1984) with soils classified as typic calciborolls with a high 

 percentage of reprecipitated calcium carbonate; the parent material is alluvium, with the 

 calcium derived from glacial till scoured from Precambrian Siyeh limestone. At 

 Rattlebone Lake (020) the landtype is 105, indicating lacustrine soils, with the 

 surrounding drainage classified as type 355 with associated non-calcareous soils. The 

 absence of Cypripedium calceolus var. parviflorum at this site is unique for occurrences 

 on the KNF, thus G passerinum may be adapted to a wider range of soil pH. The soils 

 are subirrigated and moist. The species reaches its southernmost limits in Montana and 

 extends north above the Arctic Circle; it is adapted to cool soils. 



4. Climate factors: Cypripedium passerinum is adapted to growing in cold climates with 

 short growing seasons, its distribution extending above the Arctic Circle. Data from the 

 climatological station at Fortine (National Oceanic and Atmospheric Administration 

 1982) at 3,000 feet elevation characterizes the climate where the species grows on the 

 KNF. From 1951 to 1980 the mean temperature normals ranged from 19.8° F in January 

 to 63.8° in July and the normal annual precipitation was 17.25 inches. The Rocky 

 Mountain Front Range in Montana, where G passerinum grows in greater numbers, has a 

 colder climate and shorter growing season than the Rocky Mountain Trench where it 

 grows on the KNF. Climate may be a factor in the low numbers of this species found on 

 the KNF. 



F. Population demography and biology 



1. Phenology: The species flowers in June and produces fruit in late June to July. It is 



reported as flowering somewhat later than Cypripedium calceolus var. parviflorum 

 (Lesica and Shelly 1991) but at sites hosting both species on the KNF they were 

 flowering concurrently in 1995. 



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