Near Arco, a town we lived in over 30 years ago in Idaho, is Craters of the Moon National Monument. Though we visited there many times and explored the mountains near by, we couldn’t remember having seen this showy wildflower, which we saw in the monument and elsewhere this trip.
From the USDA website:
Mentzelia laevicaulis – smoothstem blazingstar
From Double Cone Quarterly:
… perennial herbs of sandy and/or rocky areas, summer-dry flood plains, washes and sometimes road cuts. What first catches the eye are the large five petaled flowers, which are light yellow. and range from about 6 to 16 cm (2.5-6.5") wide when fully expanded. The flowers are further adorned by a wide fountain-like display of numerous long stamens. The five innermost stamens, which alternate with the petals, have widened, petal-like filaments. The plants begin to produce flowers around June and continue to do so until about October. Another striking feature of this species are the whitish-shining stems. Although Mentzelia laevicaulis translates as "smooth-stemmed Mentzelia," this is in comparison to other Mentzelia species, for at least the upper stems are rough to the touch due to a light coat of short and stiff barbed hairs.
Mentzelia laevicaulis is widely distributed in temperate western North America, where it is occurs suitable habitats in California, Nevada, Oregon, Washington, British Columbia, Idaho, Montana, Wyoming and Utah. It is found in diverse regions, ranging from lowland deserts to mountainous areas up to about 2700 m. (8,000′).