Tufted to clump-forming, with a sheaf of erect to ascending stems 20-50cm tall, from a short fleshy taproot. Leaves linear, 1.5-5cm long. Flowers in branched leafy cymes, 2-3.5cm long by l-2cm broad, with bright yellow, fimbriate petal lobes, late spring to summer, followed by much smaller pale yellow cleistogamous blooms. Much of North America, in dry prairies and other open habitats. Prone to mildew attack in cultivation.