Slickspot Peppergrass
This tiny mustard is easy to overlook because its entire world is a scattered set of clay-rich slickspots within Idaho sagebrush.
Artwork inspired by Mary Hallock Foote
Slickspots collect water and develop unusual soil chemistry, creating openings where this plant can germinate with less competition. White four-petaled flowers reveal the mustard family, while round flattened fruits help confirm the species. Population counts swing sharply because dormant seed can wait through unfavorable years.
The habitat is more visible than the plant and just as important. Never step or drive through a bare-looking slickspot, especially when wet; tire tracks and footprints alter drainage and crust. Wildfire followed by invasive annual grass can transform the surrounding system and increase future fire.
- Range
- Southwestern Idaho only
- Habitat
- Clay-rich slickspots
- Status
- Federally threatened
Quick guide
- First field mark
- A small annual or biennial mustard with white four-petaled flowers and rounded flattened seed pods
- Then confirm
- Slickspots—small, clay-rich, sparsely vegetated depressions—within southwestern Idaho sagebrush-steppe
Field evidence for Slickspot Peppergrass
- Establish structure
- Treat “A small annual or biennial mustard with white four-petaled flowers and rounded flattened seed pods” as a field hypothesis.
- Challenge the first view
- After the overall form, confirm Slickspots—small, clay-rich, sparsely vegetated depressions—within southwestern Idaho sagebrush-steppe.
- Check when and where
- Place Slickspot Peppergrass within “Slickspots—small, clay-rich, sparsely vegetated depressions—within southwestern Idaho sagebrush-steppe”.
- Keep behavior natural
- Document Slickspot Peppergrass from durable ground, including its neighbors, without picking, bending, or clearing vegetation.
Good to know
Exact populations can be sensitive and many occur where access is restricted. Use agency-led viewing or public interpretive sites; a “bare patch” is not an invitation to stand closer, because soil structure is the habitat.
Notice these
- A small annual or biennial mustard with white four-petaled flowers and rounded flattened seed pods
- Slickspots—small, clay-rich, sparsely vegetated depressions—within southwestern Idaho sagebrush-steppe
- Germinates and flowers in wet spring conditions, while seeds can remain dormant through dry years; abundance varies dramatically with precipitation.