Rheum nobile

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Noble rhubarb
Rheum nobile (photo Bill Baker).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Polygonaceae
Genus: Rheum
Species:
R. nobile
Binomial name
Rheum nobile
Botanical details Rheum nobile.jpg
Botanical details

Rheum nobile, the Sikkim rhubarb [1] or noble rhubarb (पदमचाल), is a giant herbaceous plant native to the Himalaya, from northeastern Afghanistan, east through northern Pakistan and India (in Sikkim), Nepal, Bhutan, and Tibet to Myanmar, occurring in the alpine zone at 4000–4800 m altitude. [2]

Contents

It is an extraordinary species of rhubarb (genus Rheum ). At 1–2 m tall, the monocarpic inflorescences of R. nobile tower above the other shrubs and low herbs in its habitat, and it is visible across valleys a mile away. [3]

R. nobile is often called a glasshouse plant because of its outer curtain of translucent bracts which pass visible light, creating a greenhouse effect, while blocking ultraviolet radiation. These are likely defenses against the increased UV-B exposure and extreme cold in its high altitude range. [4] It also provides a safe haven for its pollinators against wind and night chill.

Description

An individual R. nobile is a conical tower of delicate, straw-coloured, shining, translucent, regularly overlapping bracts; the higher ones have pink edges. Large, glossy, green radicle leaves, with red petioles and nerves, form a broad base to the plant. Turning up the bracts reveals membranous, fragile, pink stipules. Within these are short branched panicles of diminutive green flowers. [5]

The root is often 1–2 m (3.3–6.6 ft) long and as thick as an arm, and bright yellow inside. After flowering, the stem lengthens and the bracts separate one from another, turning a coarse red-brown. As the fruit ripens, the bracts fall away, leaving a ragged-looking stem covered with panicles of deep brown pendulous fruits. As Hooker put their appearance: "In the winter, these naked black stems, projecting from the beetling cliffs, or towering above the snow, are in dismal keeping with the surrounding desolation of that season." [5]

Photographs of its inflorescence, supposedly showing a “pagoda flower”, have been frequently shared on social media along with the false claim that it only blooms once every 400 years in the Himalayas. But several other websites, including an online catalogue on the flowers and foliage in India, reveal that it blooms annually in June and July. On the other hand, it is, in fact, one of the largest plant species in the Himalayas and grows in mountain ranges of Nepal, Sikkim, Bhutan and Tibet at altitudes between 4000m-4800 m. The plant can grow up to two meters (6 feet) in height and it is also known as Sikkim Rhubarb or Noble Rhubarb. [6]

Karyotypy

R. nobile has a chromosome count of 2n=22. [7]

Bracts

Actual size model of Rheum nobile, exhibited in the National Museum of Nature and Science, Tokyo, Japan. Rheum nobile Replica.jpg
Actual size model of Rheum nobile, exhibited in the National Museum of Nature and Science, Tokyo, Japan.

The bracts of R. nobile are 110-170 μm thick and do not differentiate into palisade and spongy layers. [8] They selectively block ultraviolet radiation while letting almost all visible light through; thus the developing flowers and the apical meristem are protected from the intense radiation found in high altitudes. The major UV blockers found in the bracts are all quercetin flavonoids: [9]

Minor UV blockers include quercetin 7-O-glycoside, quercetin itself, kaempferol glycoside, and feruloyl ester.

Edibility

The stems are pleasantly acidic, and they are consumed by the local people, who call the plant Chuka. The hollow of the stem contains a good deal of limpid water. [5]

History

Scene from one of Hooker's sketches Rheum nobile scene.jpg
Scene from one of Hooker's sketches

A description of R. nobile was first published by Joseph Dalton Hooker and Thomas Thomson in 1855. Hooker wrote:

"The present is certainly the most striking of the many fine alpine plants of Sikkim; and though in every botanical character, as also in the acid juice of the stem, a genuine Rhubarb, it differs so remarkably in habit and general appearance from any of its congeners, that at first sight it could not be recognized as one of them. I first saw it from a distance of fully a mile, dotting the black cliffs of the Lachen valley at 14,000 feet [4,300 m] elevation, in inaccessible situations, and was quite at a loss to conceive what it could be; not was it till I had turned back the curious bracteal leaves and examined the flowers that I was persuaded of its being a true Rhubarb." [5]

Related Research Articles

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<span class="mw-page-title-main">Rhubarb</span> Species of herbaceous perennial plant with fleshy, sour edible stalks

Rhubarb is the fleshy, edible stalks (petioles) of species and hybrids of Rheum in the family Polygonaceae, which are cooked and used for food. The plant is a herbaceous perennial that grows from short, thick rhizomes. Historically, different plants have been called "rhubarb" in English. The large, triangular leaves contain high levels of oxalic acid and anthrone glycosides, making them inedible. The small flowers are grouped in large compound leafy greenish-white to rose-red inflorescences.

<span class="mw-page-title-main">Alpine plant</span> Plants that grow at high elevation

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<i>Rheum palmatum</i> Species of flowering plant

Rheum palmatum is a species of flowering plant in the knotweed family Polygonaceae. It is commonly called Chinese rhubarb, ornamental rhubarb, Turkey rhubarb or East Indian rhubarb.

<i>Rheum</i> (plant) Genus of flowering plants

Rheum is a genus of about 60 herbaceous perennial plants in the family Polygonaceae. Species are native to eastern Europe, southern and eastern temperate Asia, with a few reaching into northern tropical Asia. Rheum is cultivated in Europe and North America. The genus includes the vegetable rhubarb. The species have large somewhat triangular shaped leaves with long, fleshy petioles. The flowers are small, greenish-white to rose-red, and grouped in large compound leafy inflorescences. Many rhubarb cultivars have been domesticated as medicinal plants and for human consumption. While the leaves are slightly toxic, the stalks are used in pies and other foods for their tart flavor.

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<span class="mw-page-title-main">Isoquercetin</span> Chemical compound

Isoquercetin, isoquercitrin or isotrifoliin is a flavonoid, a type of chemical compound. It is the 3-O-glucoside of quercetin. Isoquercitrin can be isolated from various plant species including Mangifera indica (mango) and Rheum nobile. It is also present in the leaves of Annona squamosa, Camellia sinensis (tea). and Vestia foetida

<span class="mw-page-title-main">Hyperoside</span> Chemical compound

Hyperoside is a chemical compound. It is the 3-O-galactoside of quercetin.

<i>Rheum rhabarbarum</i> Species of plant

Rheum rhabarbarum is a species of flowering plant in the family Polygonaceae, native to a region stretching from southern Siberia to north and central China. It has been harvested from the wild for centuries for its root, which was harvested for use as a popular medicine in Europe and Asia. It was later cultivated for its root in England and Russia. It is considered to be one of the species involved in the development of culinary rhubarb, for which the scientific name R. rhabarbarum is sometimes (erroneously) used.

<i>Rheum australe</i> Species of flowering plant

Rheum australe, synonym Rheum emodi, is a flowering plant in the family Polygonaceae. It is commonly known as Himalayan rhubarb, Indian rhubarb and Red-veined pie plant. 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. The plant is found in the sub-alpine and alpine Himalayas at an altitude of 4000 m.

<i>Rhaponticum scariosum</i> Species of flowering plants in the daisy family Asteraceae

Rhaponticum scariosum, common name giant scabiosa, is a perennial herbaceous flowering plant of the genus Rhaponticum of the family Asteraceae.

<i>Rheum maximowiczii</i> Species of flowering plant

Rheum maximowiczii is a large herbaceous perennial plant species in the genus Rheum (rhubarbs) from the mountains of Central Asia where it grows in Kazakhstan, eastern Uzbekistan, Tajikistan, Kyrgyzstan and northeastern Afghanistan.

<i>Rheum ribes</i> Species of plant

Rheum ribes, the Syrian rhubarb or currant-fruited rhubarb, or warty-leaved rhubarb, is an edible wild rhubarb species in the genus Rheum. It grows between 1000 and 4000 m on dunite rocks, among stones and slopes, and is now distributed in the temperate and subtropical regions of the world, chiefly in Western Asia to Afghanistan and Pakistan and also in ladakh(Kargil) region of India. The Syrian rhubarb is a partially commercial vegetable collected from wild patches in Eastern and Southern Anatolia, Northern Iraq and partly Northwestern Iran in early spring. Rheum ribes is considered as a valuable medicinal species in herbal medicine.

<i>Rheum rhaponticum</i> Species of flowering plant

Rheum rhaponticum, the false rhubarb, rhapontic rhubarb or rhapontic, is a plant species in the genus Rheum found in the wild. It is the only Rheum species found only in Europe, and is now restricted to the Rila mountain range in south-western Bulgaria. It was introduced to other countries in Europe. It is considered to be one of the parents of the modern culinary rhubarb.

<i>Teucrium gnaphalodes</i> Species of flowering plant

Teucrium gnaphalodes is a plant species in the genus Teucrium. It is endemic to the Iberian Peninsula and grows at altitudes between 200 and 1500 m. It flowers from March to July.

<i>Iris hookeriana</i> Species of plant

Iris hookeriana is a plant species in the genus Iris, it is also in the subgenus Iris and in the section Pseudoregelia. It is a rhizomatous perennial, from the Himalayan mountains of India and Pakistan. It has long pale green or yellow green leaves, long slender stem and fragrant blue, purple or lilac flowers, that are mottled with a darker colour. It is cultivated as an ornamental plant in temperate regions.

Rheum lhasaense is a plant from eastern Tibet belonging to the genus Rheum in family Polygonaceae. It is a mid-sized rhubarb species with triangular leaves and spherical fruit.

<i>Rheum webbianum</i> Species of plant

Rheum webbianum is a species of herbaceous perennial rhubarb-relative in the family Polygonaceae from the southwestern Himalayan region, known in (Indian) English as Indian rhubarb, Gilgiti rhubarb or small Himalayan rhubarb.

References

Notes

  1. ↑ Eisenreich, Dan (1996–2010). "Rhubarb Botanical Information". The Rhubarb Compendium. Retrieved 2 April 2019.
  2. ↑ "Rheum nobile". Flora of China. eFloras.org. Retrieved 2006-06-11.
  3. ↑ "Eastern Himalayan alpine shrub and meadows". Terrestrial Ecoregions. World Wildlife Fund.
  4. ↑ Iwashina et al. p.101
  5. 1 2 3 4 Hooker p.94
  6. ↑ URL: http://www.flowersofindia.net/catalog/slides/Sikkim%20Rhubarb.html
  7. ↑ Ruirui, Liu; Wang, Ailan; Tian, Xinmin; Wang, Dongshi; Liu, Jianquan (2010). "Uniformity of karyotypes in Rheum (Polygonaceae), a species-rich genus in the Qinghai-Tibetan Plateau and adjacent regions". Caryologia Firenze. 63 (1): 82–90. doi: 10.1080/00087114.2010.10589711 . S2CID   86616077 . Retrieved 26 March 2019.
  8. ↑ Tsukaya pp.60-61
  9. ↑ Iwashina et al. 104-106
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