During the summer season, river trails more prominently display plant species like arrowleaf balsamroot, American brooklime, bigleaf lupine, Douglas's spirea, Indian paintbrush, and monkeyflower plants. On islands in the river, wildflowers occasionally grow after their seeds bloom after falling into the water and accumulating over time. The area is noted for a rare species of Penstemon known as Penstemon peckii, a wildflower that appears in 7 different colors, which is endemic to the Sisters area.
During the summer season, river trails more prominently display plant species like arrowleaf balsamroot, American brooklime, bigleaf lupine, Douglas's spirea, Indian paintbrush, and monkeyflower plants. On island locations in the river, wildflowers occasionally grow after their seeds have dispersed into the water and accumulate over time. The area is noted for a rare species of Penstemon known as Penstemon peckii, which appears in 7 different colors and is native to the Sisters region.