The Calabash Tree: 2. Flowers and bees

My Calabash Tree (Crescentia cujete) has been flowering for months now LINK. A few young fruits were eventually located. Obviously there was pollination. As the flowers open in the late evening the pollinators could be either moths or bats.

The flower buds swell in the early evening and bloom by 5.40 pm (above). Starting with the tips of the petals, the flowers slowly unfold to expose the four stamens and a central style (video below).

So far, I have only seen a few bees visiting the flowers, attracted by the faint perfume (video below).

But on the evening of 7th September 2017 I suddenly became aware of numerous bees attracted to this single flower. There were a few others blooming nearby but only this particular flower got all the attention from the bees.

Initially Stingless Bees (Trigona sp.) visited, filling their pollen baskets with the yellow pollen. Then the Asian Hive Bees (Apis cerana) flew in and the smaller Stingless Bees were mostly displaced.

The bees were fighting for the pollen, literally “digging” them from the anthers as soon as the anther sacs burst open. Some of the bees crawled to the base of the flower to feed on the nectar but most of them were filling their pollen basket with pollen.

By morning rings of petals were found on the ground below (above), including that visited by numerous bees as shown in the video. Only the bare flower with its long style remained on the branch (below). The next day the bare flower (below) also dropped to the ground. I can only conclude that bees are not the pollinating agent.