''Rheum australe'',

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

''Rheum emodi'', is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

in the family

Polygonaceae The Polygonaceae are a Family (biology), family of flowering plants known Common name, informally as the knotweed family or smartweed—buckwheat family in the United States. The Botanical name, name is Basionym, based on the genus ''Polygonum'', ...

. It is commonly known as Himalayan rhubarb, Indian rhubarb and Red-veined pie plant. It is a medicinal herb used in the Indian

Unani Unani or Yunani medicine (Urdu: ''tibb yūnānī'') is Perso-Arabic traditional medicine as practiced in Muslim culture in South Asia and modern day Central Asia. Unani medicine is pseudoscientific. The term '' Yūnānī'' means 'Greek', ref ...

system of

medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, and formerly in the European system of medicine where it was traded as ''Indian rhubarb''. The plant is found in the sub-alpine and alpine Himalayas at an altitude of 4000 m.

Description

The plant has a 1.5-2m high stem. Its stem is stout, red, and streaked green and brown. The large leaves are heart-shaped or roundish with a heart-shaped base, and greenish-red in colour. The basal leaves can be up to 60 cm wide. It has dark reddish-purple or yellow flowers in late spring to summer, in densely-branched clusters, in a inflorescence up to 30 cm long. The inflorescence enlarges greatly when in fruit. Rheum australe Oulu 04

Similar species

According to the 2003 key in the ''

Flora of China The flora of China consists of a diverse range of plant species including over 39,000 vascular plants, 27,000 species of fungi and 3000 species of bryophytes.Wu, Z. Y., P. H. Raven & D. Y. Hong, eds. 2006. Flora of China. Vol. 22 (Poaceae). Sci ...

'', 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 1 cm-sized fruit, purple-red flowers, and the surface of the rachis of

panicle In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...

being densely pubescent. It is the only rhubarb in this group to have purple-red flowers as opposed to various shades of white.

Karyotypy

A 1947 study found plants of ''R. emodi'' a

chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...

count of 2''n''=22, but the same study found plants labelled as ''R. australe'' to be 2''n''=44. It is possible that this karyotypic diversity indicates the existence of one or more

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

, because the

polyploid Polyploidy is a condition in which the biological cell, cells of an organism have more than two paired sets of (Homologous chromosome, homologous) chromosomes. Most species whose cells have Cell nucleus, nuclei (eukaryotes) are diploid, meaning ...

forms would essentially be reproductively isolated.

Distribution

Native to

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

Nepal Nepal, officially the Federal Democratic Republic of Nepal, is a landlocked country in South Asia. It is mainly situated in the Himalayas, but also includes parts of the Indo-Gangetic Plain. It borders the Tibet Autonomous Region of China Ch ...

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

Bhutan Bhutan, officially the Kingdom of Bhutan, is a landlocked country in South Asia, in the Eastern Himalayas between China to the north and northwest and India to the south and southeast. With a population of over 727,145 and a territory of , ...

, and

Sikkim Sikkim ( ; ) is a States and union territories of India, state in northeastern India. It borders the Tibet Autonomous Region of China in the north and northeast, Bhutan in the east, Koshi Province of Nepal in the west, and West Bengal in the ...

Ecology

It grows on grassy or rocky slopes, crevices and moraines, forest margins, near streams and between boulders in specific zones. ''

Impatiens glandulifera ''Impatiens glandulifera'', Himalayan balsam, is a large annual plant native to the Himalayas. Via human introduction it is now present across much of the Northern Hemisphere and is considered an invasive species in many areas. Uprooting or cutt ...

'' in the Valley of Flowers,

Uttarakhand Uttarakhand (, ), also known as Uttaranchal ( ; List of renamed places in India, the official name until 2007), is a States and union territories of India, state in North India, northern India. The state is bordered by Himachal Pradesh to the n ...

, India.

Cultivation

It is said to be quite hardy and readily propagated.

Chemical constituents

Hydroxyanthracene Hydroxyanthracenes are a class of natural Phenols, phenolic compounds. They can be found in ''Cassia alata'' and ''Cassia senna'' (sennoside A, sennosides A, sennoside B, B, sennoside C, C and sennoside D, D). References

Natural phenols ...

derivatives are mainly

emodin Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is an organic compound. Classified as an anthraquinone, it can be isolated from rhubarb, buckthorn, and Japanese knotweed ('' Reynoutria japonica'' syn. ''Polygonum cuspidatum''). Emodin is part ...

chrysophanol Chrysophanol, also known as chrysophanic acid, is a fungal isolate and a natural anthraquinone. It is a C-3 methyl substituted chrysazin of the trihydroxyanthraquinone family. Chrysophanol (other names; 1,8-dihydroxy-3-methyl-anthraquinone and c ...

and their glycosides. Other hydroxyanthracene derivatives are

rhein Rhein may refer to: Places * Rhine, a major river in Europe () * Rhein, a village in the municipality of Morsbach in North Rhine-Westphalia, Germany * Rhein (Ostpreussen), a former name of the town Ryn in Poland * Rhein, Saskatchewan, a village w ...

aloe emodin Aloe emodin (1,8-dihydroxy-3-(hydroxymethyl)anthraquinone) is an anthraquinone and an isomer of emodin present in aloe latex, an exudate from the aloe plant. It has a strong stimulant-laxative action. Aloe emodin is not carcinogenic when applie ...

and

physcion Parietin is the predominant Cortex (botany), cortical pigment of lichens in the genus ''Caloplaca'', a secondary metabolism, secondary product of the lichen ''Xanthoria parietina'', and a biological pigment, pigment found in the roots of curled do ...

and their glycosides.Shah C.S., Quadry J.S., and Bhatt J.G., Planta Med., 22, 103(1972).

References

{{Taxonbar, from1=Q15247758, from2=Q7320476 australe Plant dyes