Flowers wake

I was extremely surprised when I realized that feral okra (Abelmoschus esculentus, aka bhindi) grew widely near the seashore around Mumbai. By most accounts, this plant originates in north-east Africa, and spread from there to South Asia and Arabia in prehistoric times, and then to the rest of the world in the modern era. There are several closely related edible plants, which seem to have been hybridized extensively over millenia and are genetically almost indistinguishable now. It is a bit surprising to find that it is as hardy as a weed, and grows in most unused land around the city. Perhaps the hot and wet conditions here suit it especially well.

This week, while watching birds around Bhandup pumping station, I spent a while looking at the flowers of this plant unfold in the morning. I had not realized that the flowers close at night, a behaviour called nyctinasty. Why would plants put on rapid bursts of growth at different parts of the petals at dusk and dawn to force the flower to open and close? There’s a lot of speculation about the function of nyctinasty in leaves. Okra leaves seemed to have remained open at night, so most of the speculations are ruled out. Since the leaves were dripping water at dawn, I guess the main function of the closing of petals must be to keep the sexual organs dry. Interesting that this question does not seem to have been investigated before.