While browsing the Internet this week, I chanced upon a newly published article (23 March 2015) titled "Invasive trees in Singapore: are they a threat to native forests?". Coming across such report on trees in Singapore was not exactly an extraordinary event. The unexpected part was that it led to the identification of a thorny tree that remained a mystery to me for the last 3 years. I took some pictures of the trees in December 2012 but was simply not able to put a name to it despite its distinctive thorny stem and branches. While reading the article, a tree by the name Flacourtia jangomas (coffee plum) stood out though there was no picture of the plant in it. I googled the name and the rest was history.

I am familiar with the 9 invasive tree species singled out in the in the article. Indeed, I had already collected their pictures. It was comforting to know that none of them was a threat to our forest. The table that I like most in the article was reproduced below with some information omitted. It provided information on when the trees was first recorded in Singapore and their potential sources.

Back in 2011, there was another article written on closely similar topic ---- naturalised tree species in Singapore titled "Casual establishment of some cultivated urban plants in Singapore". Interestingly, there was no overlap on the 7 trees described in that article versus the 9 trees in the above more recent report. I had summarised some of the information from the 2011 article in a table format below:

One relatively common cultivated tree that was missing in the 2 reports was Adinobotrys atropurpureus (Purple Milletia). The fallen large seeds could be often seen germinating under the parent trees. I had seen tall matured trees in the midst of the Central Catchment Nature Reserve as well as Bukit Timah Nature Reserve. The 2009 Singapore Flora checklist had listed it as an exotic tree. However, the book Tall Tales published by the Singapore Botanic Garden (2014, page 26) noted the possibility of it being a native plant while NPark's Flora website had indicated Singapore as one of its native range. After all, it may indeed be a native tree. Over the last few years, I noticed that NPark has been systemically removing this tree from the roadside and replaced it with some other trees. I guess the large round seeds that littered the road might endanger the motorcyclists.