Cascade mariposa lily is a beautiful, perennial wildflower arising from deep seated, tunicated bulbs. The plant is erect, arising from 5 to 30 cm in height. The leaf is generally basal, about 10 to 30 cm long and 2 to 15 mm wide. The leaf has parallel venation and is elliptical in shape, tapering to a point at both ends. Two to several narrow, leafy bracts may be found below the flower cluster.
One to five flowers may found atop the stem. The flowers have three yellowish-white petals which are obovate in shape. The petals measure from 15-22 mm long. The inner side of each petal is typically very much bearded with long, slender hairs (see uppermost photo). The 3 sepals are lanceolate to lance-ovate in shape with pointed tip, and measure 1.5-2 cm long. The sepals are cream-colored or may have a light purplish tinge with a deep purple spot. The fruit are pendant, of elliptic shape and 3 winged.
Cascade mariposa Lilies live in loose volcanic soils at medium to higher elevation, typically found in open forests and drier meadows.
Cascade mariposa lilies are found in the southern Washington Cascades, roughly from Mt. St. Helens and Mt. Adams south to the Columbia River. The range extends southward through the Cascades to the Three Sisters area in the Central Oregon Cascades. In the Columbia River Gorge, it may be found between the elevations of 2700'-4700' from Silver Star Mt. in the west to Monte Carlo in the east.