Angsana trees (Pterocarpus indicus), introduced into Singapore in the early 19th century, belong to the family Leguminosae (Papilonaceae). A common wayside tree that can grow well within a short period of time and with a wide-spreading crown that provides shade, it was only extensively and systematically planted in Singapore in the late 19th century and the 20th century.

Origin and distribution
Angsana trees are native to the southern part of the east coast of Peninsular Malaysia and was noted growing in Malacca as early as 1778. 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. 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. In Singapore, it is widely distributed along major roads because of the Garden City campaigns of the lat 1960s and early 1970s. Even before this, its shade inspired the colonial government to plant the tree along the Peninsular.

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

The leaves are simple pinnate compound, with 7 to 9 leaflets alternately arranged and ending in a terminal leaflet. 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. The leaflet is broadly elliptical, with a pointed tip and is rounded at the base. Flowers are small (about 1.5 cm), yellow, faintly fragrant reminiscent of orange blossoms. They grow in large bunches 15 to 30 cm long. Upon blooming following the right triggers, they last for only one day. Subsequently, the yellow flowers carpet the ground where it falls. Fruits are disc-like flattened pods, measuring 4 to 5 cm wide with a swollen centre containing one to several seeds. The fruits do not split open when matured. They turn brownish, pulpy and very few of them germinate.

Flowering in Angsana is related to temperature variations and rainfall. In habitats where there is a marked dry season, the Angsana flowers twice a year. Leaf shedding followed by flowering occur conspicuously after a period of dry weather. However, Angsanas in Singapore do not flower twice a year as a distinct dry period is uncommon. They do not flower at all, unless there is an exceptional hot and dry period, for example, in 1982 and 1983.

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. The wood can also produce red dye. Various parts of the tree, including the dark red latex, are used in native medicine.

However, it is for its shade and beauty that the Angsana has been used extensively, planted along roads and in parks in Singapore. When fully grown, its majestic crown, with large slender branches drooping down to the ground, is a sight to behold. The tree is quick growing, easily transplanted with high survival rates. It provides much needed shade within the shortest possible time and is used as a shade tree for other crops.

From the early 19th century onwards, the tree was systematically planted in the then British colonies of Malacca and Penang. It was extensively planted in Singapore in the late 19th century, lining almost every important promenade. However, in 1885, a disease broke out in Malacca spreading to the north to Penang around 1908, and south to Singapore by 1914. The spread of the disease in the Angsana trees in Singapore was so prevalent that it killed many of the infected trees. Rows upon rows of the trees were cut down in an effort to contain the contagious spread but in vain. The disease appeared to travel along transport routes, giving rise to the theory that the disease was spread by traffic movement. However, the cause of the trees' infection was suspected to be fungal disease. Today, most of these original Angsana trees in Singapore are long gone but a few remnants of those plantings can be found along Bukit Timah Road.

In 1967, Singapore launched its Garden City campaign to beautify its environment with greenery. From the late 1960s to the early 1970s, the Angsana became a popular choice of planting for the campaign. During the initial phase of the campaign, there was an urgent demand for planting materials that were easy to grow within a short span of time. Angsana trees were ideal for this purpose as it could provide "instant trees". Large-sized stem and branch cuttings from the tree developed roots easily once planted. Within a relatively short span of time, the tree grows to an advanced stage. As a result, the trees were extensively planted along newly-opened roads and in newly completed parking lots requiring immediate shade.

However, an inherent weakness of the Angsana is that it is prone to branch breakage, especially during heavy storms. In recent years, it has been infected by a fungal disease known as the "Angsana Wilt", which has killed many of the trees. Hence, there have been increased efforts to plant more resistant varieties in place of the Angsana. In spite of this, it remains a popular shade and ornamental tree in Singapore. Today, Angsana trees are seen growing along both major roads such as Orchard Road, and ordinary roads in many Housing Development Board (HDB) estates.

It is the national tree of the Philippines.

Variant Names
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, Sana, Andaman redwood, Burmese redwood.

Nureza Ahmad

Jensen, M. (1995). Trees commonly cultivated in Southeast Asia: An illustrated field guide (p. 179). Bangkok, Thailand: FAO Regional Office for Asia and the Pacific (RAP).
(Call no.: RSING 582.160959 JEN)

Rao, A. N., & Wee, Y. C. (1989). Singapore Trees (p. 275). Singapore: Singapore Institute of Biology.
(Call no.: RSING 582.16095957 RAO)

Tee, S. P., & Wee, M. L. (2001). Trees of our garden city: A guide to the common trees of Singapore. (pp. 142-143). Singapore: National Parks Board.
(Call no.: RSING 582.16095957 TRE)

Wee, Y. C. (1989). A guide to the wayside trees of Singapore (pp. 7-11). Singapore: Singapore Science Centre.
(Call no.: RSING 582.16095957 WEE)

Wee, Y. C. (2003). Tropical trees and shrubs: A selection for urban planting (p. 143). Singapore: Sun Tree Publishing.
(Call no.: RSING 582.16095957 WEE) 

Further Readings
Burkill, I. H. (1966). A dictionary of the economic products of the Malay Peninsula. Kuala Lumpur: Ministry of Agriculture and Co-operatives.
(Call no.: R 634.909595 BUR)

The information in this article is valid as at 2004 and correct as far as we can 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.

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