Redshank (plant)

The Redshank (Persicaria maculosa, formerly Polygonum persicaria) is a perennial plant from the Knotweed family Polygonaceae. It is also called Persicaria, Redleg or Spotted Ladysthumb.

There are three varietes known:
 * Polygonum persicaria var. angustifolium Beckh.
 * Polygonum persicaria var. persicaria
 * Polygonum persicaria var. ruderale (Salisb.) Meisn.

synonyms include P. maculata, P. persicaria, P. ruderalis, P. ruderalis, P. vulgaris, P. dubium, P. fusiforme, P. minus and P. puritanorum.

It grows up to 1 m high, and has narrow, lancet-shaped leaves 8-10 cm long. The leaves often have a brown or black spot. The white, pink or red flowers are in dense panicles and flower from early summer to late autumn.

It is native to Europe and Asia, where it can be mistaken for Polygonum minus, but P. minus has narrower leaves, usually less than 1 cm wide, while its ear is slimmer.

It has been introduced to North America and is naturalised in all mainland states, being found along roadsides, riverbanks, and on fallow ground. In the USA, it is very similar to Pennsylvania smartweed, but Redshank has a fringe of hairs at the top of the ocrea, something which Pennsylvania smartweed lacks.

Cultivation and uses
This plant contains persicarin and tannins. In medicine, Redshank is used against diarrhoea and infections. Fresh leaves have been used to staunch bleeding.

The leaves and young shoots may be eaten as a palatable and nutritious leaf vegetable. It is often seen as a weed and rarely cultivated.

A yellow dye can be produced from this plant with alum used as a mordant.