Calochortus greenei

Greene's Mariposa Lily is native to Oregon and California and is included in the CNPS Inventory of Rare and Endangered Plants, listed as: rare, threatened, or endangered in CA and elsewhere. C. greenei has an affinity for the serpentine soil of the Klamath-Siskiyou region. It is perennial and blooms in the summer months. Its branching stalk ranges in height from 12-30 inches. The flowers are bell-shaped and erect, with 1-5 blooms per flower cluster. The flowers each have three sepals and three petals, of 3-4 inches in length, that are light purple in color with darker shades of purple at the bottom. The inside of the petals are lightly haired. A basal leaf about 20cm in height does not wither while C. greenei is flowering. Greene's Mariposa Lily grows on shrubby hillsides and open places. It prefers sun and part shade 

Sources:

http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Calochortus+greenei

http://www.wildflower.org/plants/result.php?id_plant=CAGR

http://www.calscape.org/Calochortus-greenei-(Greene's-Mariposa-Lily)?srchcr=sc56c2c5550e883