French Sorrel is a plant in the buckwheat family

Polygonaceae

Polygonaceae is a family of flowering plants known informally as the "knotweed family" or "smartweed family"— "buckwheat family" in the United States. The name is based on the genus Polygonum and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name refers...

, used as a culinary herb. Its common names include buckler sorrel, shield-leaf sorrel, and sometimes the culinary name

Culinary name

Culinary names, menu names, or kitchen names are names of foods used in the preparation or selling of food, as opposed to their names in agriculture or in scientific nomenclature. The menu name may even be different from the kitchen name...

 "green-sauce".

As a culinary herb, it is used mainly in salads. The flavour of French Sorrel is slightly bitter or tangy, spiced with a hint of lemon, the sharp flavour is due to oxalic acid

Oxalic acid

Oxalic acid is an organic compound with the formula H2C2O4. This colourless solid is a dicarboxylic acid. In terms of acid strength, it is about 3,000 times stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations...

. French sorrel is hardy

Hardiness (plants)

Hardiness of plants describe their ability to survive adverse growing conditions. It is usually limited to discussions of climatic adversity. Thus a plant's ability to tolerate cold, heat, drought, flooding, or wind are typically considered measurements of hardiness. Hardiness of plants is defined...

in most regions, tolerating frost, full sun and short dry spells. It grows quickly to a clump up to 1 metres (3.3 ft) in diameter, with long leaves up to 10 centimetres (4 in) in width.