[2] It is the only Rheum species found only in Europe, and is now restricted to the Rila mountain range in south-western Bulgaria.

[5] Rheum rhaponticum is a robust perennial herbaceous plant growing from a woody rhizome.

Plants from the Rila mountain range have been compared to those in Linnaeus's herbarium and are considered to be the same species.

[8] Throughout most of the Middle Ages and early modern era Europeans were unaware of the source for these roots, which had become known as rheum barbarum (among many other names, including the Persian raved).

Botanists such as Leonhart Fuchs (in 1542) and Rembert Dodoens (in 1554) identified a species of thistle in the family Asteraceae, Rhaponticum scariosum, as the source of the root, thus this plant was used to produce an inferior rhubarb.