Angsana

Background

Introduced into Singapore in the early 19th century, the Angsana tree (Pterocarpus indicus) belongs to the family Fabaceae/Leguminosae (Papilionoideae).¹ Its fast growth and dense, wide-spreading crown has made the Angsana a popular shade tree in Singapore.²

Origin and distribution
Angsana trees are native to the southern part of the east coast of Peninsular Malaysia.³ It is widely distributed in Southeast Asia and is popular worldwide, planted in countries such as Africa, India, Sri Lanka, Taiwan and Okinawa, Hawaii and Central America.⁴ In its natural habitat, it grows on flat coastal plains behind mangrove swamps, or along inland rivers in forests where the dry season is not pronounced.⁵

Description
The Angsana is a large deciduous tree of up to 30 to 40 m tall and 2 m in diameter.⁶ It has a dense, wide spreading, dome-shaped crown with drooping lower branches.⁷ The trunk is buttressed and the bark is grey-brown, becoming scaly and fissured with age.⁸ When cut or slashed, dark red resin oozes out.⁹ The wood varies in colour from light yellow to golden brown to reddish brown, and has a camphor or cedar scent.¹⁰

The leaves are simple pinnate compound, with seven to nine leaflets alternately arranged and ending in a terminal leaflet.¹¹ They range in size from 20 to 50 cm long with each leaflet approximately 5 to 12 cm long and 4 to 8 cm wide.¹² The leaflet is broadly elliptical, with a pointed tip and is rounded at the base.¹³ Flowers are 1.5 cm long, yellow and grow in large bunches, exuding a faint fragrance reminiscent of orange blossoms.¹⁴ The buds develop inconspicuously until the right stimulus – usually a sudden drop in temperature – causes them to bloom simultaneously.¹⁵ The blooms last for only a day and are then shed, carpeting the ground with yellow petals.¹⁶ Fruits are disc-like flattened pods, measuring 4 to 5 cm wide with a swollen centre containing one to several seeds.¹⁷ The fruits do not split open when matured. They turn brownish, pulpy and very few of them germinate.¹⁸

In places that experience a marked dry season, the Angsana sheds its leaves and remains bare for a few weeks after which it grows new leaves and flower buds. In Singapore, where there is no pronounced seasonality, the tree could take several months to renew its crown as the leaf change takes place branch by branch from the bottom up.¹⁹ In addition, flowering may occur once every few years or for only a part of the tree at one time.²⁰

Usage
Commercially known as narra, Angsana wood is said to be the best fine-furniture wood in Malaysia, and is used for furniture making, cabinets, decorative veneers, interior trimming and novelty items.²¹ The resin, called kino or dragon’s blood, is used as an astringent.²² Various parts of the tree are used in traditional medicine, for example, the bark is used to treat diarrhoea and dysentery.²³

The Angsana was extensively planted as a shade tree in Malaya and Singapore in the 19th century.²⁴ However, a fungal disease, known as Fusarium Wilt (or Angsana Wilt), attacked the trees on the Malay Peninsula and spread to Singapore in 1914.²⁵ By 1922, many of the Angsana trees in Singapore, specifically those along Connaught Drive and in the Dhoby Ghaut and Tanglin areas, either perished or were removed in a bid to arrest the epidemic.²⁶

The Angsana was then widely planted during the initial phase of Singapore’s Garden City campaign, which was launched in 1967.²⁷ There was an urgent demand for rapid planting materials and the Angsana became a popular choice as it is readily propagated by seeds or cuttings and tends to do well after transplanting.²⁸ Over 20,000 “instant” Angsana trees were thus planted between 1969 and 1982 to provide immediate greenery and shade along roadsides, in parks and other locations island-wide.²⁹

However, its appeal soon wore off as the fast-growing Angsana required frequent pruning lest its drooping branches, which are prone to breaking in heavy rains, became a hazard to motorists and pedestrians.³⁰ Moreover, there were fears that the dreaded fungal disease could return and threaten the Garden City image of Singapore.³¹ A severe outbreak in the 1980s saw the removal of more than 800 infected trees.³² Since then, efforts have been made to study the cause of the disease, develop measures for treatment and prevention, as well as cultivate and plant resistant varieties.³³

The Angsana is the national tree of the Philippines.³⁴

Variant Names³⁵
Common name: Angsana.
Scientific name: Pterocarpus indicus.
Other names: Sono kembang (Indonesia), Angsana (Malaysia), Narra (Philippines), Duu baan, Praduu baan (Thailand)
Other common names: Sena, Andaman redwood, Burmese rosewood, Philippine Mahogany



Author
Nureza Ahmad



References
1. National Parks Board, Singapore, Trees of Our Garden City: A Guide to the Common Trees of Singapore (Singapore: National Parks Board, 2009), 156 (Call no. RSING 582.16095957 TRE); Michael Jensen, Trees Commonly Cultivated in Southeast Asia: An Illustrated Field Guide (Bangkok, Thailand: FAO Regional Office for Asia and the Pacific (RAP), 1995), 179. (Call no. RSING 582.160959 JEN)
2. National Parks Board, Singapore, Trees of Our Garden City, 156.
3. Wee Yeow Chin, Tropical Trees and Shrubs: A Selection for Urban Planting (Singapore: Sun Tree Publishing, 2003), 143. (Call no. RSING 582.16095957 WEE)
4. Wee, Tropical Trees and Shrubs, 143.
5. Jensen, Trees Commonly Cultivated in Southeast Asia, 179.
6. National Parks Board, Singapore, Trees of Our Garden City, 156; Jensen, Trees Commonly Cultivated in Southeast Asia, 179.
7. Jensen, Trees Commonly Cultivated in Southeast Asia, 179.
8. Wee, Tropical Trees and Shrubs, 143.
9. Wee, Tropical Trees and Shrubs, 143.
10. National Parks Board, Singapore, Trees of Our Garden City, 157; Jensen, Trees Commonly Cultivated in Southeast Asia, 179.
11. Wee, Tropical Trees and Shrubs, 143.
12. Wee, Tropical Trees and Shrubs, 143.
13. Wee, Tropical Trees and Shrubs, 143; National Parks Board, Singapore, Trees of Our Garden City, 156.
14. Wee, Tropical Trees and Shrubs, 143; Wee Yeow Chin, A Guide to the Wayside Trees of Singapore (Singapore: Singapore Science Centre, 1989), 8. (Call no. RSING 582.16095957 WEE)
15. Wee, A Guide to the Wayside Trees of Singapore, 8; Wee, Tropical Trees and Shrubs, 143.
16. E. J. H. Corner, Wayside Trees of Malaya, vol. 1 (Kuala Lumpur: Malayan Nature Society, 1988), 416. (Call no. RSING 582.1609595 COR)
17. Wee, Tropical Trees and Shrubs, 143.
18. A. N. Rao and Wee Yeow Chin, Singapore Trees (Singapore: Singapore Institute of Biology, 1989), 275. (Call no. RSING 582.16095957 RAO)
19. Corner, Wayside Trees of Malaya, 416.
20. Wee, A Guide to the Wayside Trees of Singapore, 8.
21. National Parks Board, Singapore, Trees of Our Garden City, 157; Wee, Tropical Trees and Shrubs, 143.
22. Wee, Tropical Trees and Shrubs, 143.
23. Wee, Tropical Trees and Shrubs, 143; Corner, Wayside Trees of Malaya, 417.
24. Wee, Tropical Trees and Shrubs, 143; C. X. Furtado, “A Disease of the Angsana Tree,” Journal of the Malayan Branch of the Royal Asiatic Society 13, no. 2 (October 1935): 163. (From JSTOR via NLB’s
eResources website)
25. Furtado, “A Disease of the Angsana Tree,” 164; “Pterocarpus Indicus Willd,” Flora & Fauna Web, accessed 6 April 2016; National Parks Board, Singapore, Trees of Our Garden City, 156.
26. Furtado, “A Disease of the Angsana Tree,” 164.
27. Wee, A Guide to the Wayside Trees of Singapore, 9; National Parks Board, Singapore, Trees of Our Garden City, 156; “S’pore To Become Beautiful, Clean City Within Three Years,” Straits Times, 12 May 1967, 4. (From NewspaperSG)
28. Wee, A Guide to the Wayside Trees of Singapore, 9; National Parks Board, Singapore, Trees of Our Garden City, 156.
29. Wee, A Guide to the Wayside Trees of Singapore, 9; Flora & Fauna Web, “Pterocarpus Indicus Willd”; Yeo Hwee Yng, “New Treatment Found for Diseased Angsana Trees,” Straits Times, 22 December 1992, 25. (From NewspaperSG)
30. Lillian Chew, “Angsanas Fall Out of Favour,” Straits Times, 20 May 1984, 8 (From NewspaperSG); Flora & Fauna Web, “Pterocarpus Indicus Willd.”
31. Chew, “Angsanas Fall Out of Favour.” 
32. F. R. Sanderson et al., “A Fusarium Wilt (Fusarium oxysporum) of Angsana (Pterocarpus indicus) in Singapore,” Gardens’ Bulletin 48 (1996): 89. (Call no. RSING 581.05 SIN)
33. National Parks Board, Singapore, Trees of Our Garden City, 157; Samantha Boh, “Five Angsana Trees Return to Esplanade Park,” Straits Times, 27 November 2015. (From Factiva via NLB’s eResources website) 
34. Flora & Fauna Web, “Pterocarpus Indicus Willd.”
35. Flora & Fauna Web, “Pterocarpus Indicus Willd”; Jensen, Trees Commonly Cultivated in Southeast Asia, 179.



Further resource
I. H. Burkill, A Dictionary of the Economic Products of the Malay Peninsula  (Kuala Lumpur: Ministry of Agriculture and Co-operatives, 1966). (Call no. RSING 634.909595 BUR)

The information in this article is valid as at 2016 and correct as far as we are able to ascertain from our sources. It is not intended to be an exhaustive or complete history of the subject. Please contact the Library for further reading materials on the topic.