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Common Name: The Cocoa Plant
Latin Name: Theobroma cacao
Family: Sterculiaceae

Range:
Probably originally from the slopes of the Andes in South America, now cultivated in virtually all tropical regions.

Abundance:
It is rare to find it growing wild, and the highest wild concentrations of it are in its endemic environment, the foothills of the Andes. It is very common overall, however, because of its value as an economical crop.

Coloration:
Greyish brown. Leaves are deciduous. The pods are white, green, or red when unripe, green, yellow, or purple when ripe. The pods that I observed were brown and cracked, because it was not fruiting season for T. cacao and the pods had died. The flowers are small and pink.

Morphology:
Reasonably small, rarely getting as tall as 20 m. Leaves are entire, alternate, and unlobed, and are up to 40 cm long. The pods grow directly on the tree trunk and can be up to 30 cm in length. Has shallow surface roots, and thin branches.

Reproductive cycle:
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Pods at different stages of development. July 2010

T. cacao is unusual because its reproductive cycle means that there are sometimes flowers and fruits on the tree simultaneously. It takes 5 to 8 months for the tiny flower bud to mature. The flowers are pollinated primarily by midges, but bees and other flies contribute as well. If the flowers are not pollinated, they die within 24 hours of maturation. Despite being hermaphroditic, T. cacao is not able to self-pollinate. When a pollinated flower dies, a seed pod forms on the tree trunk. It takes 4-5 months for the pod to grow to full size and then another month to ripen. T. cacao reproduction takes place perpetually because it occurs on such a long time scale.

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Immature pods, July 2010















Habitat:
T. cacao grows in tropical and subtropical environments and can tolerate a precipitation of 4.8-42.9 dm annually, and a mean annual temperature of around 25 degrees C. They typically grow in lowland regions below 300 m. Wind-intolerant, so tend to grow in rainforests when not cultivated on farms. They are shade-tolerant and thrive in well-drained, deep soils. Shallower soils do not support them as well. It is an understory tree and does best without direct sunlight.

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Sign on a T.cacao plant. July 2010

Interaction with other species:
As I mentioned previously, T. cacao is pollinated primarily by flies and midges. There are several hundred kinds of fungi which parasitize this tree, since it grows best in shady and humid environments. Certain fungi cause diseases which can devastate crop yields on plantations of these crops. Some of these include Botryodiplodia theobromae (pod rot), Cephaleuros viruscens (Algal spot), and Marasmius perniciosis (South American witches broom). Humans and T. cacao have a very fond symbiotic relationship; T. cacao is cultivated ubiquitously in the tropics for the production of cocoa, cocoa butter, and chocolate. The genus name, “Theobroma,” actually means “Food of the Gods.” In both the Aztec and Mayan mythologies, T. cacao was given to mankind as a gift from the gods. In fact, there are probably few plants in the world that are as beloved and vital to man as the cocoa plant (And even among the beloved plants of the world, T. cacao is the most innocuous.)

Personal Experience:
T. cacao is easy to identify by their characteristic pods growing directly on their trunks. They were all in the shade, with only one observed specimen found in a more exposed location. This one was directly next to the bridge, by the river, and while it was in the shadow of a grove of larger trees it was exposed on one side so that it would have direct sunlight for part of the day. Its pods were withered and did not seem as healthy as those in the forest, although this might have just been a consequence of the time of cycle.


References:
http://www.xocoatl.org/tree.htm

http://www.hort.purdue.edu/newcrop/duke_energy/theobroma_cacao.html