Argemone pleiacantha  Prickly Poppy
ANNUAL.  A tall, coarse, showy plant with extremely prickly greenish-blue leaves, large silky white flowers, and oval, prickly seedpods.  In the Empires, common on roadsides, cow tanks, other recently disturbed ground.  Blooms in May-late summer.  A. mexicana has smaller, creamy yellow flowers.  I have not found it in the Empires yet, but it is well established at a cow tank just west of Davidson Canyon.
FAMILY:  Papaveraceae (Poppy Family)