Obione Gaertner, Fruct. Sem. Pl. 2: 198, plate 126. 1791

Plants annual or perennial, monoecious to subdioecious or less commonly dioecious. Leaves usually with or, uncommonly, without Kranz anatomy. Staminate flowers with calyx lobes crested or not. Pistillate flowers lacking or rarely with a perianth (in A. covillei, A. pleiantha, and A. suckleyi), enclosed by a pair of bracteoles. Bracteoles cuneate to ovate or obovate united at least to middle, faces with tubercles or crests or smooth. Seeds erect; radicle typically superior (except in A. pleiantha), erect, tip adjacent to styles.

Species ca. 33 (27 in the flora): mainly w North America, also Old World.