Wrightia tinctoria

Wrightia tinctoria, Pala indigo plant or dyer's oleander,[1] is a flowering plant species in the genus Wrightia found in India, southeast Asia and Australia. It is found in dry and moist regions in its distribution. Various parts of the plant have been used in traditional medicine, but there is no scientific evidence it is effective or safe for treating any disease.

Wrightia tinctoria
Flowers
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Gentianales
Family: Apocynaceae
Genus: Wrightia
Species:
W. tinctoria
Binomial name
Wrightia tinctoria
(Roxb.) R.Br., Mem. Wern. Soc. 173. 1809.

Description

Morphology
Illustration from The Botanical Register showing leaves and flowers
Leaves of W. tinctoria
Simple leaves with opposite leaf arrangement. Upper leaves are glabrous.
Close-up of the white flowers. Flowers are insect pollinated.

It is a small to medium-sized deciduous shrub or tree, ranging from 3 m to 15 m in height[2] but also reaching up to 18 m.[3] The bark is smooth, yellowish-brown and about 10 mm thick, producing a milky-white latex. Leaves are simple, oppositely arranged, ovate, obtusely acuminate and are 10–20 cm long and 5 cm wide. Leaves are glabrous and sometimes pubescent beneath.[2] Leaf stalks are very short. The flowers appear (in India) from March to May, peaking from April to June.[2][3] White flowers appear in corymb-like cymes, 5–15 cm across, at the end of branches. Flowers have five white petals 2–3 cm long which turn creamish yellow as they age. The flowers have oblong petals which are rounded at the tip, and are similar to flowers of frangipani. Fruiting is in August[2] and the fruit is cylindrical, blackish-green speckled with white, long horn-like and united at tip. The seeds are brown and flat with bunch of white hairs.[3] Seed dispersal is by wind and pollination is by insects.[3] In his 1862 book on timber trees of South Asia, Edward Balfour mentions its distribution across the then Madras Presidency of British India especially in the Coimbatore jungles, and reports that it was "very common in all forests of Bombay".[4] In the same book, Balfour quotes William Roxburgh's comparison of the whiteness of the wood as "coming nearer to ivory than any I know". Earlier in 1824, the plant specimens were presented by the British East India Company to the Royal Horticultural Society as illustrated and recorded in botanical register founded by Sydenham Edwards and at the time published by James Ridgway.[5]

Phytochemistry

The plant contains wrightial, a triterpenoid phytochemical,[6] along with cycloartenone, cycloeucalenol, β-amyrin, and β-sitosterol isolated from the methanol extract of the immature seed pods.

Taxonomy

The following are considered to be synonyms of Wrightia tinctoria:[7]

Distribution and habitat

It is mainly found in Australia, India, Myanmar, Nepal, Timor and Vietnam.[2] Within India, it is found in most of the peninsular and central India except the northern and north-eastern states.[3]

Ecology

It is a slow to moderate-growing plant. Plants commence flowering when about 5–8 years old. It grows in a wide range of soil types ranging from arid, semi-arid, gravely or rocky soils and moist regions, especially on dry sandy sites or hillsides and valleys. The tree responds well to coppicing, and also produces root suckers.[2] It tolerates moderate shading and is often found as undergrowth in deciduous forests.[2] It also tolerates high uranium levels in soils.[2] In India, the fungus Cercospora wrightia is known to cause leaf spot disease of Wrightia tinctoria.[8]

Uses

The flowers, leaves, fruits and seeds are edible.[8] The tree is harvested from the wild as a medicine and source of a dye and wood. Leaves are extracted as fodder for livestock. The leaves, flowers, fruits and roots are sources of indigo-yielding glucoside, which produces a blue dye or indigo- like dye. About 100–200 kilos of leaves are needed to prepare 1 kilo of dye.[2] It is occasionally planted as an ornamental in the tropics. The branches are trampled into the puddle soil in rice field for green manuring. It is recommended as a good agroforestry species as it intercrops well.[2] Bharath art and crafts artisans said the wood of Wrightia tinctoria is used extensively in Channapatna (a toy town of India) for carving and lacquer work of world famous Channapatna Toys. The timber is high in quality and valuable. The white wood is used for turnery, carving, toy making, matchboxes, small boxes and furniture. High levels of extraction is resulting in it becoming scarce in some regions.[8] The sap added to milk has been reported to have preservative properties; the milk will remain fresh for some time, the taste remaining unaltered.[8]

Traditional medicine

In Ayurveda and other traditional medicine practices, the plant is called shwetha kutaja and its seeds are called indrayava or indrajava.[9] There is no high-quality clinical evidence that it is safe or has any beneficial effect.

See also

References
  1. Deleuze, Joseph Philippe François (1823). History and description of the Royal Museum of Natural History : published by order of the administration of that establishment. Paris: A Royer. p. 704. ISBN 9781173911034. Retrieved 21 April 2016.
  2. Orwa; et al. "Agroforestree Database: a tree reference and selection guide version 4. 0" (PDF). World Agroforestry Centre. Retrieved 21 April 2016.
  3. Kavitha, A. "Common Dryland Trees of Karnataka: Bilingual Field Guide. Ashoka Trust for Research in Ecology and the Environment". India Biodiversity Portal. ATREE. Retrieved 21 April 2016.
  4. Balfour, Edward (1862). The Timber Trees, Timber and Fancy Woods: As Also the Forests of India and of Eastern and Southern Asia. London: Cookson & Co, Union Press. pp. 358. wrightia tinctoria.
  5. Sydenham, Edwards (1825). The Botanical Register: Each Number is to Consist of Eight Coloured Figures of Exotic Plants : Accompanied by Their History and Mode of Treatment : the Designs to be Made from Living Plants, Volume 11. Piccadilly, London: James Ridgway. Retrieved 21 April 2016.
  6. Wrightial, a new terpene from Wrightia tinctoria. Ramchandra P.; Basheermiya M.; Krupadanam G. L. D.; Srimannarayana G. Journal of natural products, 1993, vol. 56, no10, pp. 1811-1812
  7. "The Plant List Version 1.1". theplantlist.org. 2013. Retrieved 21 April 2016.
  8. Ba, N.; Thin, N.N.; Tonanon, N.; Sudo, S. (1995). "Wrightia R.Br". proseanet.org. PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. Retrieved 21 April 2016.
  9. "Plant Details for a Wrightia tinctoria R.BR". envis.frlht.org. Retrieved 2019-09-18.
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