Rheum australe, synonymRheum emodi, is a flowering plant in the family Polygonaceae.[1] It is commonly known as Himalayan rhubarb,[2][3]Indian rhubarb[2] and Red-veined pie plant.[2] It is a medicinal herb used in the Indian Unani system of medicine, and formerly in the European system of medicine where it was traded as Indian rhubarb.[4] The plant is found in the sub-alpine and alpine Himalayas at an altitude of 4000m.[5]
The plant has a 1.5-2m high stem.[2][3] Its stem is stout, red, and streaked green and brown.[2][3] The large leaves are heart-shaped[3] or roundish with a heart-shaped base,[2] and greenish-red in colour.[3] The basal leaves can be up to 60cm wide.[2]
It has dark reddish-purple[2] or yellow flowers in late spring to summer,[3] in densely-branched clusters, in a inflorescence up to 30cm long. The inflorescence enlarges greatly when in fruit.[2]
According to the 2003 key in the Flora of China, this species is distinguished from other entire-leaved rhubarbs in China with leaves having a wavy or crisped margin; R. wittrockii, R. rhabarbarum, R. webbianum and R. hotaoense, by having less than 1cm-sized fruit, purple-red flowers, and the surface of the rachis of panicle being densely pubescent. It is the only rhubarb in this group to have purple-red flowers as opposed to various shades of white.[6]
Karyotypy
A 1947 study found plants of R. emodi a chromosome count of 2n=22, but the same study found plants labelled as R. australe to be 2n=44. It is possible that this karyotypic diversity indicates the existence of one or more cryptic species, because the polyploid forms would essentially be reproductively isolated.[7]
It grows on grassy or rocky slopes, crevices and moraines, forest margins, near streams and between boulders in specific zones.[5]Impatiens glandulifera in the Valley of Flowers, Uttarakhand, India.[2]
Cultivation
It is said to be quite hardy and readily propagated.[3]
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