2 Montana distribution: Previously known from three sites in 

 southern Beaverhead County. A new county record was collected 

 in 1993 from the Anaconda-Pintlar Range in Granite County. 



3 Occurrences in the study area: One population was 

 discovered with subpopulations along Tex and Cabin Creeks m 

 the southern part of the area. 



P HARTTAT 



"Moist montane to alpine areas (Dorn 1984)." The population 

 in the study area occurred in a broad alluvial valley m moist 

 bottomland dominated by Potentilla fruticosa, Juncus balticus, 

 and Muhlenbergia ricbardsonis . Other associates were 

 Antennaria microphylla. Iris missouriensis, and Taraxacum 

 officinale. The soil was silty clay. The habitat was 

 degraded with many exotic and "increaser" species present. 



D. POPULATION BIOLOGY 



Population numbers were not estimated. The two subpopulations 

 covered less than 2 acres. Plants had mature fruit in late 

 July. 



E. MANAGEMENT CONSIDERATIONS 



This species mainly known from southern Beaverhead County, and 

 all four of these are impacted by livestock grazing, some 

 heavily (Lesica 1988, 1990). Although the grazing response of 

 this rare species is not known, the habitat is so restricted 

 and populations are so small that it is recommended for BLM 

 sensitive species designation. 



Thelypodium sagittatum (Nutt.) Endl . ex Walpers 

 Slender thelypody 



A. DESCRIPTION 



1. General description: This is a biennial in the Brassicaceae 

 (mustard family) . The basal leaves have short petioles while 

 the stem leaves are sessile and have prominent ear-like 

 appendages at their bases. The flowers are borne in racemes 

 and have 4 pink to purple sepals, 4 white to purple petals, 6 

 stamens, and a single pistil with an entire stigma. The fruit 

 is a long, narrow silique, which is slightly contracted 

 between the seeds. See slide 19 in Appendix E. 



2. Technical species description (quoted from Hitchcock and 

 Cronquist 1964) : 



Glaucous biennial from a simple taproot, glabrous 

 throughout to hirsute at the base, 3-7 dm tall, the stem 

 rather freely branched; basal and lowermost cauline 

 leaves oblanceolate to elliptic-oblanceolate , 4-10 cm 



46 



