Halimolobos virgata (Nutt.) Schulz 

 Twiggy halimolobos 



A. DESCRIPTION 



1. General description: Plants of this species in the 

 Brassicaceae (mustard family) are biennials and have a rosette 

 of toothed basal leaves with petioles. The leaves on the 

 flowering stems are smaller and lack petioles. The flowers 

 have 4 sepals, 4 white petals, 6 stamens and a single pistil. 

 The fruit is a silique which is not compressed in cross 

 section or contracted between the seeds. 



2. Technical species description (quoted from Hitchcock and 

 Cronquist 1964) : 



Biennial (apparently sometimes flowering the first year) 

 with a simple caudex; stems 1- several, simple to freely 

 branched, 1-3.5 dm tall, more or less grayish (especially 

 below) with a mixture of longer, simple or forked, 

 straight hairs and finer, shorter, more freely branched 

 hairs; leaves numerous, those of the basal rosette 

 petiolate, lanceolate to oblanceolate, 3-6 cm long, 5- 

 15(18) mm broad, denticulate to dentate; cauline leaves 

 several, reduced, at least the upper ones sessile and 

 auriculate; racemes many-flowered; pedicels slender, 

 ascending, 7-11 mm long; sepals often purplish; petals 

 white, usually prominently pinkish- or lavender-veined, 

 about 4 mm long; siliques nearly or quite erect, terete- 

 quadrangular or very slightly compressed, glabrous, 1.5-4 

 cm long, about 1 mm broad, not tortulose, the valves 

 strongly nerved; style 0.2-0.5 mm long; stigma small, not 

 lobed; seeds numerous, closely crowed, irregularly 

 biseriate, not margined or winged; cotyledons incumbent. 



3. Diagnostic characters: Coarsely hairy leaves with toothed 

 but not lobed margins, clasping stem leaves, and erect fruits. 

 It looks like a large Descurainia, but the leaves are not 

 lobed. 



B. GEOGRAPHIC DISTRIBUTION 



1. Species range: Hitchcock and Cronquist (1964) list "Yukon, 

 Alberta, and Saskatchewan to eastern Idaho, Wyoming, Utah, and 

 Colorado" as its distribution. Also occurs in Montana. 



2. Montana distribution: Two sites are known from the 

 Sweetgrass Hills in Liberty County, one site in Sheridan 

 County, and three now in Beaverhead County, including the two 

 new records . 



3. Occurrences in the study area: Two populations were found, 

 one in Pileup Canyon in the southern part of the area, and one 

 in Limekiln Canyon in the northeast. 



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