Subalpine mariposa lily is another species of restricted distribution — I could have included it in my list of narrow-range endemics of the Pacific Northwest, I suppose, but it is more common than the plants in that series (starting with Delphinium viridescens). It is found in south-central Washington and north-central Oregon, where it grows in “open forest in loose volcanic soils” (via Flora of North America). These plants were encountered on one of the trails around Birds Creek Meadow, on Yakama Nation land near Mt. Adams, in early August.
To see the diversity of flower form in Calochortus subalpinus, see: Calochortus subalpinus via Calphotos. To read more about the plant, see Calochortus: Mariposa lilies & their relatives: Calochortus subalpinus.