Cannonball Tree:
Sea Slug-esque Flowers, Shiva's Tree, and Pre-Columbian Transoceanic Voyages

Couroupita guianensis

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I had seen pictures of the cannonball tree (Couroupita guianensis, Lecythidaceae) in my tropical plant books for years, always with its large distinctive cannonball-esque fruits. But I had never seen a picture of the flowers, and so the first time I laid eyes on its gargantuan blooms at Fairchild Tropical Gardens in Florida, I was completely and utterly awed and enchanted. I may be going out on a limb here, but I find the flowers oddly reminiscent of nudibranchs (sea slugs). Now, I know some of you may be thinking to yourselves “what in the tarnation are nudibranchs?”  I assure you, this is a tangent worth pursuing, even if it is totally unrelated to our flower-at-hand. Give a quick click on this link for some real-life sea slug eye candy – nudibranchs, and then come back and look at the pictures of the cannonball flowers. Now, tell me if I’m crazy.
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Close-up of the Cannonball tree fruits, Photo courtesy of Marc Williams, plant-geek extraordinaire  http://www.botanyeveryday.com

In the land of personal floral superlatives, cannonball tree would get my vote for the number one most unusual flower. After dissecting hundreds of flowers, and explaining floral parts year after year to students, it is unusual for me to be so botanically tongue-tied. There is the usual pattern of stamens surrounding the pistil, and endless variations on the theme, but this flower eluded my best floral deductions. That’s because it has two sets of stamens: the typical fertile stamens (which produce pollen capable of pollinating and fertilizing other flowers) and fodder staminodes (which produce non-fertile pollen; food for bees visiting the flower). Look at the picture below–on the right side of the flower are the purple fodder staminodes and on the left are the fertile stamens surrounding a little white nipple-like pistil.

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Staminodes are modified stamens (male flower parts), which typically do not produce pollen, and instead serve another function for the flower. Some staminodes are simply beautiful and serve to attract pollinators, others may have specialized hairs, which aid in elaborate pollination strategies. The cannonball tree produces nectarless flowers and thus offers up pollen as its sole reward to pollinators- in this case bees are the primary pollinators, along with bats (to a lesser degree). Many flowers share this strategy; typically, in this arrangement, the stamens serve double duty as fertilizing agents and pollinator-attractor.  They do this by producing extra pollen, some of which will be eaten, and some of which will serve in pollination. But the cannonball tree produces fodder pollen, infertile pollen whose sole purpose is to attract and feed pollinators, who will brush up against the fertile pollen and transfer it to another flower.

Cannon ball tree with its flowers born on leafless branches originating from the central trunk

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The cannonball tree is native to the tropical forests in the Amazon basin in northeastern South America and also the islands of the southern Caribbean. It has been used traditionally as an anti-microbial and anodyne. There is some controversy on its native status in India and Thailand. In India, the tree is revered, and planted near Shiva temples. It is called Shivalinga in Hindi, and Nagalingam in Tamil. Some proponents of pre-columbian transoceanic voyages cite fossil evidence and written historical records of Couroupita guianensis in Asia as proof of transcontinental trade.

Personally, I do not find it especially far-fetched that non-Europeans found a way to travel by ocean around the world before Columbus. Nor do I find it hard to believe that the sailors would replicate the voyage after returning home, thus establishing trade routes carrying useful medicinal herbs, spices, foods and livestock. Apparently, there is fossil and linguistic evidence of non-native plants (typically edible and medicinal species) occurring in new locales, presumably brought from continent to continent, before Columbus (or the Vikings) traveled to North America.

The snake-like leafless flowering and fruiting branches, which originate from the trunk. Fairchild Tropical Gardens, 2012

Close-up of the Cannonball tree fruits, Photo courtesy of Marc Williams, plant-geek extraordinaire http://www.botanyeveryday.com

The cannonball fruit is thought to have been originally eaten and dispersed by giant ground sloths, which are now extinct. In modern times, peccaries have been observed eating the fruit. In the tropics, where the cannonball tree is planted for its beautiful and aromatic flowers, there are signs on the trees warning people to stay away from the base of the tree, as its heavy fruit falls to the ground randomly.

For more information on the botany of Cannonball tree, and more images, please visit the Lecythidaceae Pages (New York Botanical Gardens)