Slickspot peppergrass is a small, rare plant that only grows in the sagebrush-steppe habitats of southwestern Idaho, including the Snake River Plain, Owyhee Plateau and adjacent foothills. The plant averages 2 to 8 inches, but can reach up to 16 inches in height. Leaves and stems are covered with fine, soft hairs, and the leaves are divided into linear segments. Flowers are numerous, white and 4-petalled.
The native plant occurs in specialized habitats known as slickspots, which are mini-playas or natric (high sodium soil) sites with distinct clay layers. Slickspots tend to be highly reflective, are usually relatively light in color and occur dispersed throughout the sagebrush-steppe ecosystem in southwest Idaho. More than 90 percent of the occupied slickspot peppergrass habitat occurs on federal lands with the remaining occupied habitat owned by the state of Idaho private land owners.
One Plant; Two Life Cycles
Slickspot peppergrass displays two different life history strategies, an annual form and a biennial form. The annual form reproduces by flowering and producing seed in its first year, and dies within one growing season. The biennial life form initiates growth in the first year as a vegetative rosette, but does not flower and produce seed until the second growing season. The proportion of annuals versus biennials in a population can vary greatly.
Altered wildfire regime (increasing frequency, size, and duration of wildfires), and invasive, nonnative plant species (e.g., Bromus tectorum) are the two primary threat factors to slickspot peppergrass. Both are further exacerbated by climate change; as well as contributing threat factors of development, habitat fragmentation and isolation, and the emerging threat from seed predation by Owyhee harvester ants (Pogonomyrmex salinus).