Ohio Perennial and Biennial Weed Guide

Family:

Buckwheat family (Polygonaceae)

Other Names:

sheep's sorrel, field sorrel, surette, horse sorrel, sour-weed, sour-grass, cow sorrel, red-weed, mountain sorrel, cuckoo-bread, gentleman's sorrel, green-sauce, ranty-tanty, sour dock, toad's sorrel.

Origin and Distribution:

Red sorrel was introduced from Europe and has become naturalized throughout the U.S. Red sorrel is common in Ohio, especially in the unglaciated eastern part of the state and on old lake beaches south of Lake Erie. Red sorrel tolerates sites with low fertility or poor drainage but will thrive in nutrient rich soils where there is little competition from other plants. It is seldom a problem in cropland, but can be troublesome in pastures, meadows, strawberries, and grass lawns. It is common in waste areas and roadsides, especially on sandy or gravelly soils where it is difficult to eradicate.

Plant Description:

Red sorrel is an herbaceous perennial that reproduces by seeds and extensive shallow horizontal roots. It is distinguished by its arrow-shaped leaves, low height, slender wiry stem with sheathed nodes, and red to rust-brown color. The creeping horizontal roots give rise to above-ground shoots that often form dense patches.

• Root System:

  Red sorrel seedlings have a fibrous root system, but eventually produce shallow horizontal roots with whitish buds from which new shoots arise. Except for fine terminal roots, the whole root system is capable of producing buds. A root fragment as small as 1/2-inch can regenerate a new shoot.

• Seedlings and Shoots:

  Cotyledons are oblong and dull green. Seedlings resemble a rosette, made up of many leaves whose shape changes with age from egg- to spade-, to arrow-shaped. The base of leaf petioles is often red or brown.

• Stems:

  Flowering stems are slender and erect, reaching heights from 6 to 18 inches. A single crown produces several tough and wiry stems that are branched at the top. At each node of the stem, a thin, greenish-yellow or silvery membranous sheath (ochrea) is attached just below the leaf stalk. The sheath surrounds the stem like a collar until it turns brown and shatters with age.

• Leaves:

  Leaves grow alternately along the stem, one leaf per node. Lower leaves are long and spade-shaped with no lobes. Middle leaves are short and almost always have a lateral lobe near the base of the leaf on each side. Upper leaves are small with no lobes or stalks.

• Flowers:

  Flowers are small and clustered along terminal and axillary branches at the tops of stems. Red sorrel is usually dioecious, meaning that female and male flowers occur on separate plants; however, male, female, and bisexual flowers can appear on the same plant. Female flowers are greenish, while male flowers are yellow to red. Flowering begins in May and can continue throughout the growing season.

• Fruits and Seeds:

  Seeds are less than 1/16th inch long, triangular or 3-sided, smooth, shiny, and reddish-brown or golden-brown. The rough, rust-brown hull often adheres to the seed.

Similar Species:

Red sorrel is difficult to confuse with other species due to its unique arrow-shaped, sour-tasting leaves.

Biology:

Red sorrel is a highly variable plant in leaf shape, color, and response to both temperature and day-length. It probably has two germination periods, one in spring and one in early autumn. Germination is increased by light, alternating temperature, and nitrate. Some populations flower and set seeds in a single year whereas others produce adventitious roots in response to short days and then flower in subsequent years. An individual crown lasts about 18 months, during which time secondary crowns develop along creeping rootstocks. The ability to form clones allows vegetative reproduction for unlimited duration; thus a clone may be decades old. Freshly mature seeds can germinate in 3 to 4 weeks, whereas buried seeds can remain viable 10 to 20 years. The small seeds used to be common contaminants of alfalfa and clover seeds, which aided its spread wherever these crops were planted. Red sorrel has a high tolerance for acid soils, but communities have been found on calcareous substrates and there are reports it germinates best in alkaline soils. Red sorrel does not tolerate shade and is not very competitive except when growing on acid and nutrient deficient soils which it tolerates better than many other species. Fertilizer, liming, and improved drainage allow other species to be more competitive and to crowd out red sorrel.

Toxicity:

Red sorrel is not considered poisonous to humans, and is often eaten as a pot-herb or green. Very rarely contact with leaves may produce a dermatitis in susceptible individuals. It produces large quantities of light pollen that is easily dispersed by wind, and is a cause of hayfever. Red sorrel contains oxalic acid, which can poison livestock if consumed in sufficient quantity; the seeds are said to be poisonous to horses and sheep.

Facts and Folklore:

• Medicinal uses for fresh red sorrel include use of juice to treat urinary and kidney diseases.

• Red sorrel is considered an indicator of acidic soil conditions; however, it also thrives in neutral or slightly alkaline soils, especially those low in nitrates.The genus name, Acetosella, means slightly acid. The word 'sorrel' derives from the French, 'sur' meaning sour.

• To some, the leaves have a lemon taste. When steeped in hot water and drained, the sugared liquid is said to resemble lemonade.

• Red sorrel has been used medicinally to treat boils and skin disorders as well as sore throats. Native Americans used it as an antidote for poison.

• Red sorrel has had many household uses, including shining furniture and removing ink spots.