Much of the forest outside of designated wilderness areas is still roadless and undeveloped. In addition to roadless acreage adjacent to designated wildernesses, a large roadless area 164,000 acres in size (as of 1992) and straddling the Montana-Idaho state line exists just west of Lost Trail Pass. This area, named for 9,154' Allan Mountain (in Idaho), lies mostly in Montana and is critical to the migration of wildlife between the wildlands of central Idaho and the Greater Yellowstone Ecosystem. The Allan Mountain area is a lower-elevation part of the Bitterroot Range that features extensive coniferous forests, steep canyons, and pockets of old-growth ponderosa pine and Douglas-fir. Within the area is Overwhich Falls, a popular attraction; hiker's gentian (gentianopsis simplex) and primrose monkey flower (mimulus primuloides), sensitive plants, are found here in wet meadows. Elk, black bear, mountain goat, pine marten, and pileated woodpecker are residents.