Rumex salicifolius is a species of flowering plant in the knotweed 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...

 known by the common name willow dock. It is native to much of western North America and it can be found in parts of Europe as an introduced species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 and a roadside weed

Weed

A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...

. It is an extremely variable plant which is generally divided into many varieties, some of which may actually be specimens of other species. In general, it is a perennial herb producing a slender stem which is prostrate and spreading or erect, growing up to about 90 centimeters in maximum length. The leaves are up to about 13 centimeters long and can be most any shape. The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 is an interrupted series of clusters of flowers, with up to 20 in each cluster, each flower hanging from a pedicel

Pedicel (botany)

A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....

. The flower has usually six tepal

Tepal

Tepals are elements of the perianth, or outer part of a flower, which include the petals or sepals. The term tepal is more often applied specifically when all segments of the perianth are of similar shape and color, or undifferentiated, which is called perigone...

s, the inner three of which are largest and usually have central tubercles.