field mint is a herbaceous perennial plant generally growing to and rarely up to tall. it has erect or semi-sprawling squarish stems. the leaves are paired in opposite positions. they are simple, long and broad. leaves are hairy, and with a coarsely serrated margin. the flowers are pale purple, but rarely white or pink. these are in whorls on the stem at the bases of the leaves. flower's length is about . it has a five-lobed hairy calyx, a four-lobed corolla with the uppermost lobe larger than the others. it has four stamens. the fruit is a two-chambered carpel.