The steep canyon walls, boulder fields, and rock crevices along the Bruneau, Jarbidge, and Owyhee Rivers provide unique habitats in an area more commonly dominated by rolling hills and wide plateaus. Several rare plants occupy the niches created by these three rivers. The Bruneau River phlox (Leptodactylon glabrum) occurs in vertical or overhanging rhyolitic canyon walls along the inner Bruneau and Jarbidge River Canyons. The entire known extent of Bruneau River phlox in Idaho occurs within approximately 35 miles on the Bruneau, West Fork of the Bruneau and Jarbidge Rivers. It is a white flowered and matted plant that clings to ledges, rock crevices, and cliffs. The vertical, cliff-side position of the Bruneau River phlox may provide protection from late season frosts (Patterson and Yoder-Williams 1984) and hazardous deposits of debris and mud during storm events.
The Owyhee River System is home to another rare plant, the Owyhee River forget-me-not (Hackelia ophiobia). Found nowhere else but this river system, this species occupies North facing vertical rhyolitic cliffs, sheltered crevices, and shady grottos. The pale blue flowers of this species contrast sharply with the backdrop of dark volcanic rock. May and June are the best time to view this species in full flower. Owyhee River forget-me-not can be found with other cliff dwelling species such as mountain snowberry, red alumroot, prickly phlox, and