Mountain sorrel is a perennial plant with a tough taproot that grows to a height of 10 to 30 cm (4 to 12 in). It grows in dense tufts, with stems that are usually unbranched and hairless. Both flowering stems and leaf stalks are somewhat reddish. The leaves are kidney-shaped, somewhat fleshy, on stalks from the basal part of the stem. Flowers are small, green and later reddish, and are grouped in an open upright cluster. The fruit is a small nut, encircled by a broad wing which finally turns red. Forming dense, red tufts, the plant is easily recognized.