Rumex arifolius, common name maiden sorrel or mountain dock, is a leafy perennial herb in the family Polygonaceae.
Rumex arifolius can reach a height of . This plant has fleshy large leaves with entire blade margins. The inconspicuous white flowers and seeds are carried on long clusters at the top of a stalk arising from the axil of leaves. The flowers are dioecious and anemophilous. They bloom from May to June.
Rumex arifolius was first described by Carl Christian Gmelin in 1806.
Maiden sorrel is native to southern Europe, and parts of northern temperate Asia.
This species prefers pine forests and mountainous meadows at elevation of above sea level.