By Barbara Fahs, Garden Guides Contributor
Woodsorrel (Oxalis corniculata and O. stricta) looks like giant clover with small yellow flowers, which occur singly or in small groups in spring. It's a low-growing perennial plant, usually no taller than eight inches, and is shallow-rooted. Sometimes called sheep sorrel or sourgrass for its tangy taste, woodsorrel's green seedpods, leaves and stems are edible (and high in vitamins A and C): They are often wildcrafted for use in salads. Do be careful if you decide to eat this plant: The oxalic acid it contains can become toxic if you eat large quantities of it. Farmers work hard to keep woodsorrel from growing in fields where their livestock graze because the oxalic acid can cause nutritional deficiencies.
The name "Oxalis" means "sour" in Greek, which refers to the acidic taste of the foliage. "Corniculata," the Latin species name, means "horned"; this refers to the appearance of the fruits.
Woodsorrel prefers cool, shady, moist environments. It grows wild in open woods, prairies, ravines, stream banks and lawns throughout the United States. In Massachusetts, woodsorrel is a common pest weed in strawberry fields, which it favors for the shade it finds among the cultivated plants.
Cultivation and Care
One of the reasons woodsorrel is difficult to control is that when its seedpods mature, seeds blast out of them explosively, spreading the seed of the next generation all over your garden. It occurs just about everywhere--even Hawaii has a species called 'ihi, which was introduced by the early Polynesian settlers.
The Kiowa Indians, of northern Texas, Oklahoma and New Mexico, called woodsorrel "salt weed." They munched on the leaves to help reduce thirst. Other Great Plains tribes fed their horses the crushed bulbs of a type of woodsorrel to make them run faster. Many plants have been used as dyes; and woodsorrel is no exception. Some tribes boiled this plant to make a yellowish-orange dye.
Weed Control Techniques
In commercial agricultural fields, a combination of chemical and non-chemical controls is said to be the most effective means of keeping woodsorrel under control. Herbicides take care of only a certain percentage of woodsorrel plants, so hoeing, hand pulling and mulching are important natural methods for making sure this weed doesn't get the upper hand in your garden. If you spread a layer of black plastic or landscape fabric over affected areas, it will keep this weed down and make your garden areas more tidy looking.