Acoraceae is the sweet flag family. Sweet flags are perennial wetland plants that grow from creeping rhizomes. The plants produce long, narrow leaves, with no stalks, that stand upright, with veins running parallel along the length of the leaf.
The genus is native to North America and northern and eastern Asia, and naturalised in southern Asia and Europe from ancient cultivation.
Although the family Acoraceae was originally described in 1820, since then Acorus has traditionally been included in Araceae in most classification systems, as in the Cronquist system.
The family has recently been resurrected as molecular systematic studies have shown that Acorus is not closely related to Araceae or any other monocot family.