Also called yellow oxalis, sheep sorrel and yellow sour grass. It is found in open woods, prairies, ravines, stream banks, and lawns.
Common wood sorrel is a plant from the Oxalis genus. It flowers for a few months during the spring, with small white flowers with pink streaks. Red/violet flowers occur, but rarely. The binomial name is Oxalis acetosella, because of its sour taste.
The leaflets are made up by three heart-shaped leaves, folded through the middle. The stalk is red/brown, and during the night or when it rains both flowers and leaves contract.
Historically, people have extracted calcium oxalate, or "sal acetosella" from the plant, through boiling. It is slightly toxic, as oxalic acid is known to interfere with food digestion.
The leaves, flowers, and bulbs can be eaten fresh or cooked. However, fresh leaves should be eaten only in moderation. The leaves and stem of this plant contain oxalic acid, which can cause poisoning if too much is eaten.
Wood sorrel contains significant amounts of Vitamin A.
The Kiowa called yellow wood sorrel "salt weed" and chewed the leaves to alleviate thirst. Several Great Plains tribes fed their horses the crushed bulbs of Gray-green wood sorrel to enhance their speed. Some tribes boiled the plant to make a yellowish-orange dye.