Mary Anna AndersonSeptember Weed - Yellow Woodsorrel

This month, Mary Anna Anderson of UNL Extension, describes a plant that is surprisingly tough and can be prolific. And thanks to John Fech, also of UNL Extension, for photos!

Weed - Oxalis stricta. Commonly called yellow woodsorrel, ladies' sorrel, oxalis, sheep sorrel, yellow oxalis, upright yellow-sorrel, lemon clover, pickle plant, sour trefoil, stickwort, and fairy bells. In France it is called pain de coucou.

Description: The leaves of this plant are pale green and divided into three heart-shaped leaflets, somewhat like clover. The overall appearance of the young plant is delicate - which is far from reality. The plant is erect when young and can get to 20 inches tall. The plant later falls over, and can root at the nodes. Flowers of yellow woodsorrel are yellow with five petals. They are up to 1/2 inch across at ends of stems in clusters of one to four. Seed pods are slender capsules with 5 ridges and pointed tips. The seed pods are explosive, spreading the seed up to 13 feet in all directions from the parent plant. The leaves and flowers fold up at night.

Yellow woodsorrel in flower, photo by John Fech, UNLWhere: Yellow woodsorrel will grow in poor and alkaline soil. Considered a weed of gardens, fields, and lawns, it grows in full sun or shade, does best in well-drained soil and can grow in nutritionally poor grounds.

Propagation: It is a weak perennial that can be an annual in many areas. It spreads readily by seed from the explosive capsule.

Poisoning: The plant contains oxalic acid and potassium oxalate. Although considered edible because a person must eat a lot of it to cause problems, people are warned to limit their intake.

Historical: It is a native plant to eastern Asia, Japan, east and central United States, and eastern to central Canada in the forested regions.

What: There are ornamental forms of oxalis, but the Oxalis stricta is considered a weed, with some edible and herbal uses. Some people think that this plant is related to the true Irish shamrock (Trifolium pretense), which is actually a clover. To confuse the matter more, the plants usually sold in the U.S. as shamrocks at St. Patrick's Day are actually oxalis plants.

Leaves of yellow wood sorrel, photo by John Fech, UNLPros: An orange dye can be made by boiling the whole plant. Medicinally, woodsorrel leaves are said to have diuretic properties, used in fever reduction, increasing appetite, and used topically to reduce inflammation. Herbalists say juice can be made from the leaves and makes a syrup used as a gargle for ulcers in the mouth. It supposedly heals wounds and stops bleeding. At one time, herbalists made a jam by blending the fresh leaves with triple their weight of sugar and orange peel. This was the basis of the cooling and acidic drink that was used as a remedy in malignant fevers and scurvy.

Wildlife: Turkeys, quail, and prairie chickens feed on woodsorrel.

Culinary: Yellow woodsorrel is high in vitamin C. The leaves and flowers can be added to salads for flavoring. Except for the root, the plant can be chewed raw to quench thirst. The green pods can be eaten raw, and are said to have a juicy crisp texture with a sour flavor similar to rhubarb. The leaves have been used to make a flavored drink that is similar in taste to lemonade, and the whole plant can be brewed as a tea. Due to the oxalic acid and potassium oxalate content, people are warned to limit intake.

Cons: It can easily take over barren areas. Woodsorrel blooms when the plant is relatively small, and continues to bloom and produce seed from spring until fall.