Stems erect, 1 to 3 feet high and usually rnore or less branched, hairy or nearly smooth. Leaves lanceolate or broader, sometimes oval-lanceolate, usually pointed at the apex and narrowed at the sessile base, or the lower leaves petioled, the margins repand-denticulate or nearly entire, 1 to 4 inches long. Flowers bright yellow, diurnal, 1 to 2 inches broad, in terminal leafy-bracted clusters; calyx segments lanceolate, spreading, the tube mostly longer than the ovary; petals four, obcordate or slightly notched at the ends. Fruiting capsules sessile or short stalked, oblong and prominently winged, smooth or pubescent, one-fourth to one-third of an inch long; stamens eight, the alternate ones longer.
In dry or sandy soil, New Hampshire to Minnesota, south to Georgia and Louisiana. Flowering from June to August.
Among the closely related species in this State are Kneiffia longipedunculata Small, with club-shaped fruit pods on stalks longer than the body of the pod; leaves narrow but flowers conspicuous;
Memoir 15 N. Y. State Museum
A. Common Sundrops - Kneiffia fruticosa
Kneiffia linearis (Michaux) Spach, with pedicels of the fruit shorter than the capsule; leaves very narrow, and Kneiffia pumila (Linnaeus) Spach, with small flowers one-half to 1 inch broad and almost sessile club-shaped fruit pods.