This native biennial plant can be 8' tall, although it is often shorter. There is usually a central stem with alternate leaves, but sometimes there will be multiple stems in open areas, creating a bushy appearance. The stems are light green or red, and are covered with white hairs. The light or olive green leaves are up to 8" long and 2" wide, but usually smaller. They are lanceolate and resemble willow leaves. The margins of the leaves are smooth or slightly dentate, and are nearly hairless. Smaller secondary leaves often appear at the axils of major leaves on the central stem. A panicle of pale yellow flowers occurs at the apex of the plant (or at the ends of major stems, if the plant is bushy). Each flower is about 1" across when fully open, with 4 petals and prominent stamens, and a long green calyx. The flowers remain open from evening to early morning, but will remain open longer on cloudy days. They have a mild lemony scent, and bloom from mid-summer to fall on mature plants. Long narrow seedpods develop, which split open from the top to release many tiny, irregular brown seeds. They are small enough to be dispersed by the wind, and can remain viable in the soil after 70 years. The root system consists of a fleshy taproot.