Lupinus lepidus is a member of the pea family; it is commonly called Prarie Lupine or Pacific Lupine. Like other members of the lupine family, L lepidus has fungal symbionts from the genus Rhizobium in nodules on its roots, so it can tolerate poor soils. L lepidus is well adapted to dry, sunny scrubland conditions; the type of scrubland it prefers is a fire-adapted community. If this type of vegetation is not periodically burned by a wildfire, taller brush tends to grow up and shade out the smaller plants like the lupines.
In recent decades humans have made an effort to prevent wildfires from occurring, even in fire-adapted plant communities. Unfortunately this effort tends to backfire, allowing dry vegetation to build up and encouraging huge, hot fires that kill all the plants, as opposed to the rapidly moving, limited extent fires that used to occur. As a result, L lepidus is becoming increasingly rare. In unburned habitats it is shaded out by brush, and in habitats that do finally burn the fires are so intense that the lupine's deep roots and the seeds lying dormant in the soil are killed.