Mints are aromatic, almost exclusively perennial, rarely annual, herbs. They have wide-spreading underground rhizomes and erect, branched stems. The leaves are arranged in opposite pairs, from simple oblong to lanceolate, often downy, and with a serrated margin. Leaf colors range from dark green and gray-green to purple, blue and sometimes pale yellow. The flowers are produced in clusters ('verticils') on an erect spike, white to purple, the corolla two-lipped with four subequal lobes, the upper lobe usually the largest. The fruit is a small dry capsule containing 1–4 seeds.