Botany Photo of the Day

Today's entry was written by UBC Botanical Garden summer student Raakel Toppila. – Daniel

Vicki of the eastern USA aka Vicki's Pics@Flickr is the photographer of today's image (original via BPotD Flickr Group Pool). Thank you!

Tacca integrifolia, also known as bat plant or white bat flower, is distributed throughout southeast Asia but can be observed elsewhere in the world where it is popular among conservatories and hobby horticulturists. Its peculiar “whiskers” are actually filiform bracteoles, or small bracts (modified leaves) which arise in the same axil as the flowers.

The unusual flowers of Tacca make one question why such an elaborate floral structure might have evolved. Often guesses can be made, much like Darwin predicted that the orchid Angraecum sesquipedale would have a pollinator with a proboscis long enough to reach its nectary. The later discovery of its pollinator in 1903, the hawk moth Xanthopan morgani praedicta, proved Darwin right.

As for Tacca, some have suggested the “deceit syndrome” as a reason for the evolution of the elaborate flowers. The resemblance of Tacca to decaying organic matter is cited as evidence that it is attempting to attract flies (sapromyiophily) to facilitate cross-pollination. Some traits associated with sapromyiophily include dark flowers and bracts, filiform appendages, trapping mechanisms and the absence of nectar – all traits that are possessed by Tacca species (Tacca integrifolia is also reported to have a musty smell). However, one study has found that Tacca species are primarily self-fertilizing and have no great need for pollinators. The as-yet unanswered question surrounding the elaborate flowers is discussed at the end of the linked article.

A scientific description of Tacca integrifolia is available via the Flora of China, while cultivation information is available from the University of Florida IFAS Extension.