"Rheum palmatum" is a herbaceous perennial related to the edible rhubarb. Rheum palmatum is a species of flowering plant in the knotweed family Polygonaceae. The species "Rheum tanguticum" is closely related to "R. palmatum". Rhubarb is an herbaceous perennial plant in the genus "Rheum" cultivated as a vegetable. The roots of "Rheum officinale" are used in traditional Chinese medicine. "Rheum rhaponticum" is a robust perennial herbaceous plant growing from a woody rhizome. "Rheum ribes" was first formally described in 1753 by Carl Linnaeus. Traditionally "Rheum ribes" has been used in Iran as sedative and mood enhancer. "Rheon" from the Persian "rewend", later became the Latin word "rheum", meaning rhubarb. It is specifically isolated from Rheum Palmatum L. It is most closely related to "Rheum". Rheum from the eyes is particularly common. It was one of three species of "Rheum" described in "Species Plantarum" volume 1. It can also be found in "Rheum maximowiczii". It is placed in the subfamily Polygonoideae, tribe Rumiceae, along with "Rheum" and "Rumex".