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Field Guide


Clay Reed-mustard

Clay Reed-mustard (Hesperidanthus argillaceus)
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Photo by Blake Wellard; Blake Wellard
Blake Wellard 2024; Blake Wellard 2024

Hesperidanthus argillaceus

NatureServe conservation status

Global (G-rank): G1
State (S-rank): S1

Utah Wildlife Action Plan status

  • SGCN

External links


General information

Hesperidanthus argillaceus is a federally listed as threatened species known only from the Uintah Basin and upper Green River shale formation of Uintah County, Utah. This rare species grows in Desert shrub or sagebrush communities on rocky slopes and shale barrens. Red Clay-Mustard has distinct long, thin stems that are topped with clusters of white four petaled flowers that are also described as slightly lilac and might bring your full attention to this humble and hardy species growing in a characteristically dry region.

Description

Hesperidanthus argillaceus is a federally listed as threatened species known only from the Uintah Basin and upper Green River shale formation of Uintah County, Utah. This rare species grows in Desert shrub or sagebrush communities on rocky slopes and shale barrens. Red Clay-Mustard has distinct long, thin stems that are topped with clusters of white four petaled flowers that are also described as slightly lilac and might bring your full attention to this humble and hardy species growing in a characteristically dry region.

Phenology

Flowers from April to June, fruits June to July. 

Diagnostic characteristics

Hesperidanthus is a small genus of flowering plants with only 5 species yet described in North America and 3 of these occur only in Utah. H. argillaceous keys out nearly last within this small group from couplets addressing floral and leaf characteristics. Clay Reed-Mustard is distinct and rare for its combination of purple, lilac, lavender flowers, oblong anthers measuring 1-1.5 mm, and sessile to subsessile leaves with their linear-lanceolate shape.

Species range

A Uintah Basin endemic, found in Uintah County, Utah. 

Threats or limiting factors

All known populations are on Federal lands leased for oil and gas reserves (USFWS 1994). Oil and gas exploration and development of wells and ancillary facilities are ongoing threats. As of 2005, the Uinta Basin was an area of intense oil and gas exploration, and some occurrences were potentially threatened by sedimentation and erosion from upslope oil and gas developments (Franklin 2005). In addition, the entire known range is underlain by oil-rich shale; oil-shale mining and processing are significant potential threats. Off-road vehicle use is also an active threat (USFWS 1994). Domestic grazing may have had an impact historically, but is not believed to be a significant threat currently due to grazing management by the BLM (USFWS 1994).

Taxonomy

No, this species does not have taxonomic discrepancies