Sheep sorrel, or Rumex acetosella, is a perennial plant common to many parts of North America that is typically considered to be an invasive weed. It is also known as field sorrel, red sorrel, sheep's sorrel, sour grass, red weed, dog-eared sorrel or sour weed. This flowering plant is a folk remedy for a number of ailments and is one of four herbal ingredients that comprise essiac tea, which is believed by some to reduce cancerous tumors. Sheep sorrel is said to be appropriate for a variety of food uses, although its chemical properties can cause liver and kidney damage in large quantities.
This wild perennial features green leaves reminiscent of arrowheads, as well as reddish stems. Blooms appear in the spring and summer. Sheep sorrel has dioecious flowers, meaning that an individual plant has only male or female flowers, both of which are required to grow near each other in order to produce seeds in late summer. The male plant produces yellowish flowers, while the female's flowers are dark red. Wind is required for pollination to occur.
Found most often in moist growing conditions in wooded or grassy areas, sheep sorrel grows quickly and aggressively whether in full sun or partial shade. It is not ideal for grazing livestock, as it provides few nutrients and could be toxic in high enough amounts. This weed thrives in loamy or sandy soil and in clay; additionally, it can grow in soil that is very acidic. Sheep sorrel is said to be hardy to US Department of Agriculture Hardiness Zone 5. The larvae of several species of butterfly feed on this ubiquitous wild plant.
Those who seek to find sheep sorrel in the wild should use caution in plant identification. This plant is sometimes located near the nightshade vine, which also features an arrow-like leaf shape. Another common source of confusion is the presence of other types of sorrel, which can be larger in size than Rumex acetosella.
As a folk remedy, this plant has historically been used for ailments ranging from inflammation to intestinal worms. Tea made from the leaves and stem is said to have a diuretic effect on the body. Essiac tea, known as an alternative medicine for cancer, contains sheep sorrel. As of 2011, there is insufficient evidence about the purported effectiveness of this treatment due to a lack of scientific studies on this topic. Sheep sorrel should not be ingested by individuals with kidney stones, hemorrhoids or varicose veins; it should also be avoided by women who are pregnant.