Oenothera speciosa 'Siskiyou' produces 2" pink, cup-shaped flowers most of the early summer. Also called Evening Primrose or Pinkladies, Oenothera 'Siskiyou' blooms are open during the day. 'Siskiyou' is a rapidly spreading perennial plant that makes a deciduous ground cover, but it should be contained as it is very aggressive. Plants spread both by rhizomes and by seed.
Oenothera speciosa is native to much of the United States, excepting the northern tier from Washington and Oregon to Maine and parts of the Rocky Mountains. It is naturally found in rocky prairies and plains, but is also commonly seen in fields, waste areas, roadsides and other disturbed areas.
Oenothera speciosa 'Siskiyou' prefers full sun and average to poor, well-drained soil. It it very tolerant of hot sites and infertile, dry soils.