A heavy smell and a remarkable sight
Walking along Raffles Avenue from the Marina hotel complex in Singapore and heading into the outskirts of Esplanade Park, you used to hit on a fabulous tall tree. It first announced its presence by giving you a very specific olfactory sensation. Some would say that the sensation was caused by the tree's heavy fragrance, others that it had a funny smell or even an odd odor. Whatever you prefer to call it, the fragrance or smell emanated from large (12 cm) white flowers, which didn't grow on branches, but were attached to the trunk of the tree by way of woody stalks that pushed right out of the thick bark and had no connection with the foliage at the top of the tree.
Getting closer you would notice something else and quite remarkable. Attached to the tree's trunk by tangled stalks you would find clusters of almost perfectly spherical, smooth brown objects, looking very much like an assortment of cannon balls (some 15-20 cm in diameter) from Napoleon Bonaparte's days. The "cannon balls" were apparently the fruits (seed-pods) of the tree. So while some blossoms were in full bloom, some of the older ones had already developed into ripe fruits, co-existing with the blossoming flowers.
Typical of the tropical rainforest
I don't know if the tree still stands there (they have erected a new theater complex in the vicinity), but it used to be known in Singapore as a cannonball tree. Anyway, there are other cannonball trees like it in the Singapore Botanical Gardens. Well, maybe not exactly like this particular specimen, because many cannonball trees have red or pink flowers, not white flowers like this one used to have (or maybe still has).
The cannonball tree is a typical tree of the rainforest. Its habit of sprouting blossoms and fruits directly from the trunk is called cauliflory by botanists. By not developing flowers in the dense foliage of the tropical rainforest, but instead on the more accessible trunk, the cannonball tree facilitates its pollination by insects and bats.
Relative of the Brazil nut
The cannonball tree (with the botanical name Couroupita guianensis) belongs to the family Lecithydaceae, along with the Brazil nut (Para nut) tree and is said to originate in Guyana in South America. I don't think that this means that it has been spread into tropical Asia by humans, only that Europeans first discovered the species in Guyana. Asian cannonball trees are rare, but they have in all probability been growing in Asia long before Europeans happened to hit on them in South America. In India the cannonball tree is actually on the endangered species list.
Edible and nutritious or toxic and dangerous?
Are the cannonballs of the cannonball tree edible? Different sources give different opinions. Some say that they are edible and occasionally eaten, but that the smell of the fruit is rather disgusting. Others maintain that they are highly toxic and recommend caution and special gloves when handling the fruit. I suspect that the cannonball tree fruits are not toxic per se, but that many people could be allergic to them.
Cannonball trees don't seem to have much practical use, but their stature (up to 20 m in height), the beautiful flowers and the curious-looking fruits make them a splendid sight. They are increasingly cultivated in private and institutional gardens in warm climates (at least subtropical, e.g. Southern Florida, North Australia).
Cannonball tree
facts:
Botanical name: Couroupita guianensis (synonyms: Couratari pedicellaris, Lecythis bracteata, Pekea couroupita), family Lecithydaceae
Appearance: a tall (up to 20 m) tropical tree with dark brown bark
Habitat: tropical rainforests in South America, Asia. Can be cultivated in warm climates.
Flowers: large (10-15 cm) cauliflorous red, pink or white flowers
Fruit: large (20 cm) cauliflorous cannonball-shaped seed pods.
Bears fruit and flowers simultaneously.
Reference:
Picture of a cannonball tree: http://community.webshots.com/photo/46515285/46516703wStFee
http://plantsdatabase.com/go/57539/
http://www.tradewindsfruit.com/cannonball_tree.htm
http://www.botgard.ucla.edu/html/MEMBGNewsletter/Volume4number4/oTX.html
On the endangered species list in India: http://www.forestlight.co.uk/endangeredspecies.html | 
