The genus
Rheum was described in 1753 by
Carl Linnaeus, initially for three species:
R. rhaponticum,
R. rhabarbarum and
R. ribes. Dioscorides calls the plant
rha, but mentions the Romans call it
rha ponticum, and it was also called
ria or
rheon. It is theorised the
Ancient Greek word
rha was derived from an ancient
Scythian name for the
Volga River in Russia,
Rā, near from where the plant was supposedly brought. (See .) In 1936
Agnia Losina-Losinskaja in
Vladimir Leontyevich Komarov's
Flora SSSR recognised 22 native species for the
USSR, and furthermore two introduced species, one variety, and one form. The 1989
Plants of Central Asia, dealing with a larger geographical remit, has Alisa E. Grabovskaya-Borodina recognising only 12 species, synonymising a great number. The
Vascular plants of Russia and adjacent states of 1995 accepted 17 species for the states of the former USSR, re-recognising many of the taxa as species. In the
Flora of China in 2003 Borodina and Bao Bojian recognise 38 species (of which 19 are endemic) in China, including a number Borodina considered synonyms in 1989.
Intergeneric relationships Rheum is placed in the family
Polygonaceae, subfamily
Polygonoideae. Within the subfamily, it is in the tribe Rumiceae, along with the two genera
Oxyria and
Rumex. It is most closely related to
Rumex. }}
Infrageneric classification In the 1998
Flora Republicae popularis Sinicae, A. R. Li proposed classifying the Chinese representatives of the genus into five
sections. These sections are distinct morphologically, but as of 2010 studies in
karyotypy, pollen morphology or molecular data (chloroplast DNA) have failed to elucidate interspecific relationships. • '
Sect. Rheum''''' - Generally mid-sized species with entire, un-lobed leaves and whitish flowers. • '
Sect. Deserticola''''' (Maxim.) Losinsk. - Smallish species native to harsh desert environments. • '
Sect. Nobilia''''' A.R. Li - Large,
monocarpic, high altitude species from the
Himalayas that create their own mini-greenhouse by having an
inflorescence tightly protected by transparent
bracts. • '
Sect. Palmata''''' Losinsk. - The largest rhubarbs to 2m tall, with
palmate, or otherwise lobed, leaves and reddish flowers. • '
Sect. Spiciforma''''' A.R. Li - Generally stemless, high altitude species with curiously hard, leathery leaves and an inflorescence with thin, spike-like
panicles. Including many dwarf species.
Acaulia Losinskaja used a slightly different classification in the
Flora SSSR in 1936:
Plants of the World Online accepts 56 species, •
Rheum inopinatum Prain •
Rheum khorasanicum Baradaran & Jafari •
Rheum kordestanicum •
Rheum kialense Franch. •
Rheum laciniatum Prain •
Rheum lhasaense A.J.Li & P.K.Hsiao •
Rheum likiangense Sam. •
Rheum lucidum Losinsk. •
Rheum macrocarpum Losinsk. •
Rheum maculatum C.Y.Cheng & T.C.Kao •
Rheum maximowiczii Losinsk. •
Rheum moorcroftianum Royle •
Rheum nanum Siev. ex Pall. •
Rheum neyshabourense Baradaran & Jafari •
Rheum nobile Hook.f. & Thomson •
Rheum officinale Baill. •
Rheum palaestinum Feinbrun •
Rheum palmatum L. •
Rheum persicum Losinsk. •
Rheum platylobum Rech.f. •
Rheum przewalskyi Losinsk. •
Rheum pumilum Maxim. •
Rheum racemiferum Maxim. •
Rheum rhabarbarum L. •
Rheum rhaponticum L. •
Rheum rhomboideum Losinsk. •
Rheum ribes L. •
Rheum spiciforme Royle •
Rheum subacaule Sam. •
Rheum sublanceolatum C.Y.Cheng & T.C.Kao •
Rheum × svetlanae Krassovsk. (
R. cordatum ×
R. maximowiczii) •
Rheum tanguticum (Maxim. ex Regel) Balf. •
Rheum tataricum L.f. •
Rheum telianum •
Rheum tibeticum Maxim. ex Hook.f. •
Rheum turkestanicum Janisch. •
Rheum uninerve Maxim. •
Rheum uzengukuushi •
Rheum webbianum Royle •
Rheum wittrockii C.E.Lundstr. •
Rheum yunnanense Sam. == Ecology ==