Pterocarpus indicus Willd.
Angsana Tree

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Pterocarpus indicus tree in bloom.
Photo by leeyu_flickr (CC BY-NC-ND 2.0)

The Angsana is a common street tree that can be found along roadsides in Singapore, particularly along Orchard Road, and in most Housing Development Board estates. It was introduced to Singapore in the early 19th century and was a popular shade tree due to its fast growth, its wide and dense crown and the aesthetic value of its blooming flowers. Although a culturally beloved tree, its susceptibility to disease and quick growth also made it a problematic street tree.

While this tree is mostly known as Angsana in Singapore, it also has many other common names used throughout the world, including: Sena, Burmese Rosewood, Philippine Mahogany, Andaman Redwood, Red Sandalwood, Padouk, Padauk, Narra and Pokok Sena. [1] This is unsurprising given its wide geographical distribution.

Its genus name is derived from pteran meaning “wing” and carpus meaning “fruit”. The species epithet indicus meaning “from india” was a term loosely used for the Orient. [2]

CONTENT 1. Description
2. Distribution and Habitat
3. Biology
4. Human Uses
5. Taxonomy









Description

Pterocarpus indicus is a large deciduous tree that grows up to 40m high and 2m in diameter, with a rounded, drooping crown. The trunk is usually fluted and is buttressed to 7m diameter at the base. The bark is scaly and slightly fissured with age.

Compound, pinnate leaves that are 20 to 50cm long. There are about 7-12 alternate leaflets, which are ovate to elliptical in shape with entire margins. The flowers are 1.5cm long, yellow and faintly fragrant. They are bisexual and grow in large axillary panicles.

Pterocarpus_indicus_Blanco1.205-cropped.jpg
Illustration of P. indicus[3]

Fruits are flattened disc-shaped pods with papery wings. About 4-5cm wide, they have a swollen centre that contains 1-3 seeds. Two forms of the species are recognised by differences in the seed portion of the pod. P. indicus Willd. forma echinatus (Persoon) Rojo has the pod covered with bristle-like spicules, whereas P. indicus Willd. forma indicus has a smooth pod. [4] [5] [6]

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Dried fruit pod of P. indicus. Photo by Amanda Lim Yue Han (2016)

Distribution and Habitat

Pterocarpus indicus has a wide range. It is native to Southeast and East Asia including: Cambodia; India; Indonesia; Malaysia; Myanmar; Papua New Guinea; Philippines; Solomon Islands; Thailand; Vanuatu. [7] It has also been introduced to other tropical regions including has been introduced to other tropical regions and countries including the Caribbean and the tropical Americas (Cuba, southern Florida/USA, Granada, Guyana, Honduras, Jamaica, Panama, Puerto Rico, Trinidad), Africa (Congo, Sierra Leone, Tanzania), Asia (India, Sri Lanka, Taiwan), and some Pacific islands (Guam, Hawai‘i, Fiji, and Samoa). [8]

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Distribution map of P. indicus [9]

In Malaysia, its natural habitat is by the sea and along tidal creeks and rivers. In Papua New Guinea, it occurs in inland forests. In Singapore, it is considered a very adaptable tree species that can grow well in a wide range of conditions from flat sandy areas near the coast to hilly areas areas with stiff clay, resulting in it being widely planted as a street tree. [10] [11]

Conservation Status

Pterocarpus indicus is classified as a Vulnerable species by the IUCN due to overexploitation of the natural subpopulations and general habitat loss. The Vietnam subpopulation is extinct and the subpopulations in India, Indonesia and the Philippines are seriously threatened. There is heavy exploitation in Peninsular Malaysia and New Guinea. However, cultivated subpopulations are widely distributed throughout the tropics. [12]

Biology

Reproduction

The tree is evergreen in equatorial climates, but deciduous in areas with seasonal rainfall. After a pronounced period of drought, the tree sheds its leaves. As new leaves appear, flowers develop. When buds come to full size, they remain unopened until mass-bloomings are triggered by unknown factors (possibly rain). In the Philippines, North Borneo and the Malay Peninsula, flowering is mostly in February-May, and occasionally in August-November. In Celebes, Moluccas, Carolines, Solomons, and New Guinea, mostly in July-December, occasionally in February-May. The opened flowers last for one day before falling, and are likely pollinated by insects such as bees. [13] [14]

The fruit takes up to 6 months to mature. Unlike most legumes, the fruit is non-dehiscent and is mainly dispersed by wind. It also floats in water and can be water-dispersed. [15]

Diseases

This tree is susceptible to a wilt disease called Fusarium Wilt caused by the fungi Fusarium oxysporum. The disease causes the leaves to turn yellow and then brown before falling off. [16] This disease killed many Angsana trees in Singapore in the early 20th Century when it spread from the Malay Peninsula to Singapore and again in the 1990s, creating problems as it had become a very common street tree by then.


Human Uses

Ornamental

Pterocarpus indicus has been planted in Puerto Rico, Malaysia and Singapore as an ornamental and shade providing tree. It is recommended for open spaces and wide sidewalks or centre dividers where shade is important and needed quickly due to its fast growth. The tree produces attractive yellow flowers. [17]

In the late 1960s the Angsana was widely planted throughout Singapore during the initial phase of the Garden City campaign because it could be easily propagated by seeds or cutting, and did well after transplanting. It became known as an “instant” tree. However, its fast growth demanded frequent pruning, as its branches were prone to breaking in the heavy Singapore rains and were hazardous to pedestrians and motorist. [18]

Then in the 1990s, an outbreak of the fungal wilt disease in the resulted in the removal of over 800 infected trees, which destroyed cultural landmarks. In response, horticulturists from the Singapore National Parks Board (NParks), have been studying causes of the disease to develop measures for treatment and prevention, and cultivated and propagated Angsana trees that were genetically resistant to the disease. [19]

It has been observed in Singapore that Javan myna (Acridotheres javanicus) and house crows (Corvus splendens) tend to form communal roosts in these large trees. In the urban environment, the crows are considered a nuisance due to their loud noises and droppings, leading to control efforts that includes pruning the trees and planting of shorter trees. [20]

Timber

The timber from the tree is a medium-heavy hardwood that is used for light to heavy construction. It is used for fine furniture, cabinetry, carving and musical instruments. The timber is marketed as Amboyna, Blanco's Narra, Burmese Rosewood, Malay Padauk, Narra, Philippine Mahogany, Prickly Narra, and Tenasserim Mahogany.

Medicine

The red latex from the tree called kino is used as in herbal remedies for tumours, especially of the mouth, and the leaves have been reported to inhibit the growth of tumour cells in mice. Kino is also applied to sores and boils as a treatment, and combined with opium to treat diarrhea. The bark of the tree is used to treat diarrhoea and dysentery.

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Kino gum from Eucalyptus rossii. Kino was originally derived from Pterocarpus erinaceus,
but became a generic name for the red tannin-rich gum from various species of trees
across the world used as medicine[21] . Photo by Nathanael Coyne (CC BY-NC-ND 2.0)

Other Uses

The flowers are a source of honey, the leaf infusion is used as a shampoo and the wood can be used as firewood. Kino is used in tanning and dyeing, and gives a reddish-coloured dye.

Cultural Significance

Pterocarpu indicus is also symbolic as the national tree of the Philippines.[22]

In Singapore, several Angsana trees have been designated as Heritage Trees by NParks. The Heritage Tree Register identifies mature and culturally important trees, to advocate for the conservation of appreciation Singapore’s natural heritage. There are 11 Angsana Heritage Trees, with two in Sentosa and the majority scattered around the Bukit Merah and central regions.[23]

A cluster of five Angsanas at Esplanade Park lent the area a Hokkien name of ‘Gor Zhang Chiu Kar’, or ‘under the shade of five trees’. This was a popular dating spot between the 1960s to the 1980s, but the trees were devastated by the fungal disease and had to be removed. In 2015, NParks transplanted five fungal-resistant Angsana trees to Esplanade Park to replace the lost trees and reinstate the landmark.[24]



Taxonomy

CLASSIFICATIONKingdom: Plantae
Phylum: Tracheophyta
Class: Magnoliopsida
Subclass: Rosidae
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae (Papilionoideae)
Tribe: Dalbergieae
Genus: Pterocarpus
Species: P. indicus

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Section on Pterocarpus indicus in Species Plantarum[25]











Pterocarpus indicus was first published by Willdenow in Species Plantarum in 1802. Willdenow describes P. indicus as: leaves pinnate, leaflets oblong tapering to a point, with no stipules, and sharp fruits. He notes that it is quite different from a species that is known from a diagram by Rumphius.

The species description is a formal scientific description which gives a newly discovered species its scientific name. It attempts to clearly describe the new species and/or distinguish it from other previously described species with a diagnosis. Often, it includes a type material and the location of its deposition[26] . Herbariums serves as such important repositories for plant species type . The holotype for the echinatus form is stored in Leiden's Naturalis Biodiversity Center and the isolectotype for the indicus form is in The New York Botanical Garden Herbarium[27]


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Type specimens for the echinatus (CC0) and indicus (CC0) forms


Synonyms

This species has been classified under many scientific names [28] :

  • Lingoum echinatum (Pers.) Kuntze
  • Lingoum indicum (Willd.) Kuntze
  • Lingoum rubrum Rumph.
  • Lingoum saxatile Rumph.
  • Pterocarpus blancoi Merr.
  • Pterocarpus carolinensis Kaneh.
  • Pterocarpus draco sensu auct.
  • Pterocarpus echinata Pers.
  • Pterocarpus indica Willd.
  • Pterocarpus klemmei Merr.
  • Pterocarpus obtusatus Miq.
  • Pterocarpus pallidus Blanco
  • Pterocarpus papuanus F. Muell.
  • Pterocarpus pubescens Merr.
  • Pterocarpus vidalianus Rolfe
  • Pterocarpus wallichii Wight & Arn.
  • Pterocarpus zollingeri Miq.

Some of these synonyms derived from when Kuntze tried to synonymise the genus name Pterocarpus Jacq with the name Lingoum in his 1891 treatise Revisio Generum Plantarum [29] .

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Excerpt from Revisio Generum Plantarum[30] arguing for renaming of Pterocarpus.

Systematics

Phylogenetics.png
A section of the phylogenetic tree of Papilionoideae showing P. indicus (red arrow). Phylogeny was inferred from matK sequences with
Bayesian inference. Branches in bold are those supported by a posterior probability of 0.99 or 1.0. GenBank accession numbers are
provided after taxon names. Modified from Cardoso[31] (CC BY 4.0)
Phylogenetic analysis places P. indicus in the Pterocarpus subclade of the Dalbergieae tribe, which also contains the Adesmia, Dalbergia subclades. Cardoso et al. analysed the plant chloroplast gene matK, which is used for DNA barcoding angiosperms[32] , and aligned the sequences of 535 Papilionoid legumes, accounting for a majority of the recognised genera in the subfamily. The phylogenetic tree was inferred using Bayesian inference to generate multiple nonautocorrelated Bayesian trees, which were then summarised into a majority-rule consensus tree, with posterior probabilities as branch support estimates. [33] Members of the Dalbergiae tribe are found to share an aeschynomenoid root nodule as a likely synapomorphy. [34]


References

  1. ^ National Parks Board, S. (Organisation). (2013). Pterocarpus indicus Willd. Retrieved October 29, 2016, from https://florafaunaweb.nparks.gov.sg/special-pages/plant-detail.aspx?id=3093
  2. ^ Gledhill, D. (2008). The Names of Plants. Cambridge University Press
  3. ^ Francisco Manuel Blanco (O.S.A.)
  4. ^ National Parks Board, S. (Organisation). (2013). Pterocarpus indicus Willd. Retrieved October 29, 2016, from https://florafaunaweb.nparks.gov.sg/special-pages/plant-detail.aspx?id=3093
  5. ^ Lee Kong Chian Natural History Museum. (2016). Pterocarpus indicus. Retrieved October 29, 2016, from http://lkcnhm.nus.edu.sg/dna/organisms/details/484
  6. ^ Orwa, C., Mutua, A., Kindt, R., Jamnadass, R., & Simons, A. (2009). Agroforestree Database: a tree reference and selection guide. Kenya: World Agroforestry Centre. Retrieved from http://www.worldagroforestry.org/output/agroforestree-database
  7. ^ World Conservation Monitoring Centre. (1998). Pterocarpus indicus. The IUCN Red List of Threatened Species 1998: e.T33241A9770599. https://doi.org/http://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T33241A9770599.en
  8. ^ J Thomson, L. A. (2006). Pterocarpus indicus (narra). Species Profiles for Pacific Island Agroforestry . Retrieved from www.traditionaltree.org
  9. ^ Missouri Botanical Garden. (2016). Tropicos.org. Retrieved from http://www.tropicos.org/Name/13032388
  10. ^ Orwa, C., Mutua, A., Kindt, R., Jamnadass, R., & Simons, A. (2009). Agroforestree Database: a tree reference and selection guide. Kenya: World Agroforestry Centre. Retrieved from http://www.worldagroforestry.org/output/agroforestree-database
  11. ^ (Pterocarpus indicus). Gardens’ Bulletin, Singapore, 34, 189–201. Retrieved from http://www.biodiversitylibrary.org/part/171680
  12. ^ World Conservation Monitoring Centre. (1998). Pterocarpus indicus. The IUCN Red List of Threatened Species 1998: e.T33241A9770599. https://doi.org/http://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T33241A9770599.en
  13. ^ Orwa, C., Mutua, A., Kindt, R., Jamnadass, R., & Simons, A. (2009). Agroforestree Database: a tree reference and selection guide. Kenya: World Agroforestry Centre. Retrieved from http://www.worldagroforestry.org/output/agroforestree-database
  14. ^ National Parks Board, S. (Organisation). (2013). Pterocarpus indicus Willd. Retrieved October 29, 2016, from https://florafaunaweb.nparks.gov.sg/special-pages/plant-detail.aspx?id=3093
  15. ^ Orwa, C., Mutua, A., Kindt, R., Jamnadass, R., & Simons, A. (2009). Agroforestree Database: a tree reference and selection guide. Kenya: World Agroforestry Centre. Retrieved from http://www.worldagroforestry.org/output/agroforestree-database
  16. ^ Sanderson, F. R., King, F. Y., Anuar, S., Pheng, Y. C., & Ho, O. K. (1996). A Fusarium wilt (Fusarium oxysporum ) of Angsana (Pterocarpus indicus) in Singapore. Gardens’ Bulletin, Singapore, 48, 89–127. Retrieved from http://www.biodiversitylibrary.org/part/151068
  17. ^ (Pterocarpus indicus). Gardens’ Bulletin, Singapore, 34, 189–201. Retrieved from http://www.biodiversitylibrary.org/part/171680
  18. ^ Nureza Ahmad. (2016). Angsana. Retrieved from http://eresources.nlb.gov.sg/infopedia/articles/SIP_405_2005-01-28.html
  19. ^ Nureza Ahmad. (2016). Angsana. Retrieved from http://eresources.nlb.gov.sg/infopedia/articles/SIP_405_2005-01-28.html
  20. ^ Peh, K. S. H. & N. S. Sodhi, 2002. Characteristics of nocturnal roosts of house crows in Singapore. The Journal of wildlife management, 1128-1133.
  21. ^ Chisholm, Hugh, ed. (1911). "Kino". Encyclopædia Britannica(11th ed.). Cambridge University Press.
  22. ^ Orwa, C., Mutua, A., Kindt, R., Jamnadass, R., & Simons, A. (2009). Agroforestree Database: a tree reference and selection guide. Kenya: World Agroforestry Centre. Retrieved from http://www.worldagroforestry.org/output/agroforestree-database
  23. ^
    Lee, M. K. (2015, November 27). Get to know these 9 well-known Heritage Trees. The Straits Times. Singapore. Retrieved from http://www.straitstimes.com/singapore/environment/get-to-know-these-9-well-known-heritage-trees
  24. ^
    Boh, S. (2015, November 27). “Five trees” take root in Esplanade Park. The Straits Times. Singapore. Retrieved from http://www.straitstimes.com/singapore/five-trees-take-root-in-esplanade-park
  25. ^
    Willdenow, K. L. (1802). Pterocarpus indicus. Species Plantarum, 3(2), 904. https://doi.org/10.5962/bhl.title.727
  26. ^
    Winston, J. (1999). Describing Species: Practical Taxonomic Procedure for Biologists. Columbia University Press. Retrieved from http://www.jstor.org.libproxy1.nus.edu.sg/stable/10.7312/wins06824
  27. ^ GBIF Secretariat. (2016). GBIF Backbone Taxonomy. https://doi.org/10.15468/39omei
  28. ^
    GBIF Secretariat. (2016). GBIF Backbone Taxonomy. https://doi.org/10.15468/39omei
  29. ^
    Kuntze, O. (1891). Revisio generum plantarum: vascularium omnium atque cellularium multarum secundum leges nomenclaturae internationales cum enumeratione plantarum exoticarum in itinere mundi collectarum ... /mit erläuterungen von Dr. Otto Kuntze. Leipzig: A. Felix [etc.],. pp193 and pp202. https://doi.org/10.5962/bhl.title.327
  30. ^ Kuntze, O. (1891). Revisio generum plantarum: vascularium omnium atque cellularium multarum secundum leges nomenclaturae internationales cum enumeratione plantarum exoticarum in itinere mundi collectarum ... /mit erläuterungen von Dr. Otto Kuntze. Leipzig: A. Felix [etc.],. pp193
  31. ^ Cardoso, D., Pennington, R. T., de Queiroz, L. P., Boatwright, J. S., Van Wyk, B.-E., Wojciechowski, M. F., & Lavin, M. (2013). Reconstructing the deep-branching relationships of the papilionoid legumes. South African Journal of Botany, 89, 58–75. https://doi.org/10.1016/j.sajb.2013.05.001
  32. ^
    YU, J., XUE, J.-H., & ZHOU, S.-L. (2011). New universal matK primers for DNA barcoding angiosperms. Journal of Systematics and Evolution, 49(3), 176–181. https://doi.org/10.1111/j.1759-6831.2011.00134.x
  33. ^ Cardoso, D., Pennington, R. T., de Queiroz, L. P., Boatwright, J. S., Van Wyk, B.-E., Wojciechowski, M. F., & Lavin, M. (2013). Reconstructing the deep-branching relationships of the papilionoid legumes. South African Journal of Botany, 89, 58–75. https://doi.org/10.1016/j.sajb.2013.05.001
  34. ^ Lavin, M., Pennington, R. T., Klitgaard, B. B., Sprent, J. I., de Lima, H. C., & Gasson, P. E. (2001). The dalbergioid legumes (Fabaceae): delimitation of a pantropical monophyletic clade. American Journal of Botany, 88(3), 503–33. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11250829