This shows they are able to withstand diseases, grow large and live long, unlike those in Singapore.
The angsana tree, or Pterocarpus indicus, has been planted in most parts of Penang. Its large canopy provides excellent shade during hot days.
In spring time, the trees bloom and lay “golden carpets” after rain, which emanates an orangy smell.
Singapore Botanic Gardens (SBG) director Nigel Taylor said Singapore’s angsana trees never grew as large as the ones in Penang, as they were often retarded by a fungal disease called the angsana wilt disease.
Taylor said this had been the case since the 1970s. He said the disease left the branches brittle and their leaves yellow.
He said researchers had found that it was due to two factors — lightning strikes and ambrosia beetles.
“The sap in angsana trees hit by lightning becomes carbonised, giving it a sugary aroma which attracts beetles to it.
“The beetle brings with it a virus.
“Penang’s large angsana trees seem to be free of this problem. I wonder why? Perhaps it is the absence of these beetles?
“And I have never seen angsana trees this large. I think this is only in Penang,” he said.
Taylor, formerly with UK’s Kew Gardens, is in town to sign a memorandum of understanding between the Penang Botanic Gardens and the SBG, to cooperate in matters of research and technology transfer.
SBG’s research has found the angsana wilt disease killed 28 trees a month between 1989 and 1995 in the republic.
In 12 years, between 1980 and 1992, a total of 800 angsana trees in Singapore had to be removed due to the disease.
In more than 90% of the cases, the cause was due to lightning strikes and beetle virus carriers.
According to a research paper by the SBG in 1996, between 1906 and 1910, some 100 angsana trees in Penang and Tapah were also killed by the disease.
The paper says the first such case was reported in Melaka between 1870 and 1880, where a “magnificent avenue of trees which adorned the sea shore” were wiped out.
Other areas such as Kuala Kubu Baru, Kuala Lumpur and Taiping had also seen many trees die due to the angsana wilt disease in the early 1900s.