Cannonball Tree – Couroupita guianensis (Lecythidaceae) – Singapore Botanical Gardens

Filmed on location at the Singapore Botanical Gardens on Nov 22nd 2016. The cannonball tree (Couroupita guianensis) from the Lecythidaceae (Brazil nut family) family is native to Neotropical forests. Its flowers are adapted for bat pollination possibly from an ancestral state of euglossine bee pollination. Here far away from its natural home, the flowers are being visited by stingless Meliponini bees. The flowers produce impressive levels of fragrance but yield no nectar. Therefore the reward for its visitors comes in the form of a special type of pollen that are actually sterile. The way male part of the flowers (Androecium) arranged are unique to the Brazil nut family. Fertile pollen bearing stamens are arranged in a ring on the upper part of the Pacman-shaped flowers. The infertile stamens forming the jaw of the Pacman are dark red turning yellow at their tips. The fertile pollen are deposited to the upper body part of the pollinators which include Xylocopid bees. You can see a variation of the same theme in a Xylocopid bee – passionflower interaction in the short video below.

The unusually large fruits are considered as a relic adaptation evolved before the extinction of the Pleistocene megafauna. Today many mammals can still break open the hard shell of these fruits and ingest seeds inside the pulp serving as seed dispersers. To be considered as a megafaunal fruit presence of fleshy pulp is a prerequisite. Since the fruit pulp produced by the members of the Lecythidaceae family is not fleshy it does not fit in the dispersal syndrome associated with megafauna.