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Slickspot Peppergrass

ESA Status: Threatened

Slickspot peppergrass (Lepidium papilliferum) is currently listed as a threatened species under the Endangered Species Act (ESA). The U.S. Fish and Wildlife Service (FWS) will also determine whether to designate critical habitat in fall 2016.

Slickspot peppergrass ranges from 4 to 12 inches in height, and has many small white flowers that resemble the garden flower sweet alyssum. The plant typically grows in “slickspots,” which are small areas within larger sagebrush habitat. Slickspot peppergrass is found only in southwest Idaho and includes: Ada, Boise, Canyon, Elmore, Gem, Owyhee, Payette, and Twin Falls Counties.

In October 1999, slickspot peppergrass was listed as a candidate species by the FWS. In order to conserve the plant and preclude the need for a federal listing, a number of private, state, and federal entities developed a Candidate Conservation Agreement (CCA). In January 2004, the FWS found that a listing was not warranted based on the extent of the plants range and abundance.

Unfortunately, following a number of legal battles, the FWS determined that the CCA for slickspot peppergrass was not sufficient to preclude the need to list the plant. In 2009, the FWS designated slickspot peppergrass as a threatened species. Governor Otter challenged that listing in federal court. Ultimately, in 2012, the court sided with Governor Otter and declared the 2009 listing determination to be invalid. The court held that FWS did not appropriately define the plant’s “foreseeable future” (i.e., the point in time in which the threats to the species would cause the plant to become endangered).

In spring 2014, the FWS created a new listing proposal with a comprehensive foreseeable future definition. The State of Idaho, via the Office of Species Conservation, provided comments on FWS’ proposed listing. The State argued that the FWS failed to give proper credence and recognition to the recent conservation efforts aimed at reducing the primary threats to the sage-steppe ecosystem, which is home to slickspot peppergrass. These conservation measures largely focus on fire prevention, suppression, and restoration; as well as, preventing further invasion of non-native grasses (i.e., cheat grass).

Despite the State’s input, the FWS re-designated slickspot peppergrass as threatened in August 2016 – more than two years after their listing proposal. The State is currently reviewing the final rule and will determine what’s best for the plant and those who rely on the land where the plant is found.

The State of Idaho commented on FWS’ 2014 proposed rules listing slickspot peppergrass as threatened and designating critical habitat. Idaho’s comments can be read at the following link (State of Idaho’s Comments; Designation of Critical Habitat for Slickspot Peppergrass).

Department of Interior final ruling for threatened status for Lepidium papilliferum (Slickspot Peppergrass)

More Information:

Species Profile for Slickspot Peppergrass – U.S. Fish & Wildlife Service

Staff Contact:

Joshua Uriarte

Slickspot Peppergrass


Slickspot Peppergrass
Slickspot Peppergrass
Photos: Sheri Hagwood, hosted by the USDA-NRCS PLANTS Database
Slickspot Peppergrass Range Map
Slickspot Peppergrass Range
Map Credit: Idaho Department of Fish and Game
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