Annual or perennial. Leaves 1-3-pinnate. Involucre of a few to many linear bracts or lacking. Rays few to numerous. Involucel of usually many linear bractlets. Calyx teeth prominent or minute. Petals usually white. Fruit sub-terete or dorsally compressed, glabrous, pubescent or hispid; primary ridges thin or thick, secondary absent; furrows 1-3-vittate; commissure broad. Inner seed face plane.