What's Blooming May 16-22: Chocolate Tree

Chocolate tree (Chocolate family)
Theobroma cacao (Sterculiaceae)
Origin: Amazonia

The genus name Theobroma means “food of the gods,” and there really is no other way in my mind to describe chocolate. What was once an understory tree growing in littoral forests in South America is now one of the most prized agricultural commodities in the world.  The trees are small and exhibit cauliflorism, the habit of flowering and fruiting directly on the branches.  The flowers themselves are small, and are pollinated by a tiny midge fly. The pods are football-shaped and yellow-orange in color, and contain forty to sixty seeds encased in a pulp.

The seeds are removed and fermented, then processed.  Before Christopher Columbus brought the beans back to Europe, chocolate was used either medicinally, or to make a frothy whipped drink by American Indians.  The main chemical constituents are theobromine and caffeine, which both add to the bitter taste, and can produce a psychotropic effect. The tree is in the same family as the African shrub from which we derive cola, another popular, slightly psychoactive beverage.

Theobroma cacao has another interesting habit called “self-incompatibility,” which inhibits self-pollination. In an agricultural scenario this is no problem, because you would have many trees planted together on a plantation, and there would be plenty of pollen to go around. When you have a single specimen planted in a greenhouse, however, this presents a problem. So how is it that our chocolate tree, which is full of fruit right now in the tropical conservatory, is able to pollinate itself, you ask? A little bit of Disney magic, actually. We received our Theobroma from the Kraft Food exhibit at Epcot back in the eighties. It is a grafted clone of a tree which pollinates itself easily, and is therefore perfect for teaching visitors to Selby Gardens exactly where their chocolate fix comes from.

Text by David Troxell