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| Alstonia scholaris | |
|---|---|
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Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Gentianales |
| Family: | Apocynaceae |
| Genus: | Alstonia |
| Species: | A. scholaris |
| Binomial name | |
| Alstonia scholaris | |
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| Occurrence data fromGBIF[3] | |
| Synonyms[2] | |
List
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Alstonia scholaris, commonly calledblackboard tree,scholar tree,milkwood ordevil's tree in English,[4] is anevergreen tree in the oleander and frangipani familyApocynaceae. Its natural range is from Pakistan to China, and south to northern Australia. It is a toxic plant, but is used traditionally for myriad diseases and complaints. It is called 'Saptaparna' in India and is the sacred tree of the 2nd Jain tirthankarAjitnatha.[not verified in body] It was first described byLinnaeus in 1767, who gave it the nameEchites scholaris.
Alstonia scholaris is a large tree growing up to 40 m (130 ft) tall (rarely to 60 m), with narrowbuttressess that extend well up the trunk, giving it a fluted appearance. The bark is gray to pale gray with numerouslenticels, and all parts of the plant exude copious amounts of white sap when broken or cut.[5][6][7][8][9][excessive citations]
The leaves are glossy dark green above and pale below, and they are arranged inwhorls of four to eight, withpetioles (leaf stalks) around 5–15 mm (0.20–0.59 in) long. The leaves are usuallyobovate (i.e. broadest near the apex) toelliptic, tapering towards the base and with a rounded tip, and there are 25 to 40 pairs of lateral veins at 80–90° to the midvein.[5][6][7][8][9][excessive citations]
The inflorescences are much branched (cymose), withpeduncles up to 7 cm (2.8 in) long, and are produced at the ends of the branches. The small tubular flowers are cream or white and strongly scented. They are about 10 mm (0.39 in) long and wide, with fiveovate lobes. Thecalyx is about 2 mm (0.08 in) long, and the flower stalks are usually as long as or shorter. Thecorolla is white and tube-like, 6–10 mm (0.2–0.4 in) long. The lobes are broadlyovate or broadly obovate, 2–4.5 mm (0.08–0.2 in), overlapping to the left.[5][6][7][8][9][excessive citations]
The fruit is a pair of long paperyfollicles measuring up to about 30 cm (12 in) long and 6 mm (0.24 in) diameter. They contain numerous flat, brown seeds about 5 mm (0.20 in) long and 1.2 mm (0.05 in) wide, which have long tufts of hairs at each end.[5][6][7][8][9][excessive citations]
This plant was originally namedEchites scholaris byCarl Linnaeus in 1767.[2][10] The Scottish botanistRobert Brown transferred it to the genusAlstonia in 1810, as part of his work on the taxonomy ofApocynaceae.[11]
The genus was named in honour of botanistCharles Alston, and thespecies epithetscholaris is a reference to the traditional use of the timber of this tree for blackboards in Myanmar.[9]
Alstonia scholaris grows in a broad range of habitats in tropical and subtropical areas, in a range of forest types fromrainforest tosavannah, on a variety of soils including alluvial, volcanic and metamorphic, and at altitudes from sea level to more than 1,000 m (3,300 ft).[6][7][8][9]
The tree is native to tropical and subtropical areas in the following countries/regions:[2]
This is a toxic plant. At high doses, an extract of the plant exhibited marked damage to all the major organs of the body in both rats and mice. The toxicity appears to depend on the plant organ studied, as well as the season it is harvested, with the bark collected in the monsoon season being the least toxic, and bark in the summer the most. Intraperitoneal administration is much more toxic than oral. Rats were more susceptible to the poison than mice, and pure-bred mice strains were more susceptible than crossbred. The toxic effects may be due to thealkaloidechitamine in the bark.[12]
The bark contains thealkaloidsditamine,echitenine,[13] echitamine[12] andstrictamine.[14] Echitamine is the most important alkaloid found in the bark, as it has been detected in all samples studied and collected from several locations. It is commercially sold as aherbal medicine.[15]
Another alkaloid detected wasPicralinal.[16]
Alstonia scholaris is the state tree ofWest Bengal, India, where it is called the chhaatim tree (inBengali,ছাতিম).[17]
During convocation the leaves ofAlstonia scholaris (saptaparni) are awarded to graduates and postgraduates ofVisva-Bharati University by the chancellor, given to him in turn by the Prime Minister of India. In recent years, supposedly to prevent excessive damage to the environment, the vice-chancellor of the University accepts onesaptaparni leaf from the chancellor on behalf of all the students. This tradition was initiated by the founder of the University,Rabindranath Tagore.[18]
The tree blossoms in the Northern Hemisphere subtropicalautumn, and its flowers are thus widely regarded as a herald of autumn in Vietnam, especially inHanoi. Calledhoa sữa, literally 'milk flower' in reference to the color, its associations with romantic love and fleeting passion have become culturally embedded in poetry and popular music.[19] However, its heady aroma has been a source of complaint and division, with some households even filing lawsuits against urban planning departments, for example in a case in 2011 in what was thenTrà Vinh province.[20]
The wood ofAlstonia scholaris has been recommended for the manufacture ofpencils, as it is suitable in nature and the tree grows rapidly and is easy to cultivate.[21] In Sri Lanka its light wood was used forcoffins. The wood close to the root is very light and of white colour, and inBorneo was used for net floats, householdutensils,trenchers, corks, etc.[22] InTheravada Buddhism, the firstBuddha is said to have usedA. scholaris as the tree for achieving enlightenment.
The 1889 bookThe Useful Native Plants of Australia states that "the powerfully bitter bark of this tree is used by the natives of India in bowel complaints (Treasury of Botany). It has proved a valuable remedy in chronic diarrhoea and the advanced stages of dysentery. It has also been found effectual in restoring the tone of the stomach and of the system generally in debility after fevers and other exhausting diseases (Pharmacopoeia of India). It is described in thePharmacopoeia of India as an astringent tonic, anthelmintic, and antiperiodic. It is held in the highest repute in the Phillippine Islands [sic]."[23] Despite its widespread traditional use as an 'antiperiodic' (a medicine which was supposed to cure the effects of malaria), it was found to have little to very weak activity against the cause of the disease,Plasmodium falciparum.[24][25] It had no effect againstGiardia intestinalis,[24] and weak effect againstEntamoeba histolytica, which both cause diarrhoea.[25]
