Plants & People: The Intersection of Botany and Human Experience

Irvingia Gabonensis: The Dika Diet

Nomenclatural History

This is a specilized species with many, many, many names. Just a few can be seen below.


Evolutionary History

Locally, the different irvingia fruits are often referred to as payo in general. There are differences among them, but there is not much historical information on the evolution of these species. However, it is known now that these relatives speciated in “diversity ‘hot spots” (Lowe et al., 2000). These are zones in which there is high genetic diversity within these similar species.

This is thought to be caused by the Pleistocene refugia dynamics. In simpler terms, there has not been a large influence of climate change since the Pleistocene era. This means there has been a relatively constant environment, leading to species having relatively similar attributes due to them being the best adaptations for fitness (Lowe et al., 2000). They are varied just slightly enough to allow for niche partitioning and stable distribution. 

Ecology & Life History

This species is an important food source for many animals in the forest. The mammals of central Africa find this to be extremely nutritious. These mammals include a diversity of species including forest elephants,  squirrels, red forest pigs, etc (Ainge & Brown, 2001). This is due to the seeds of the dika fruit being high in nutrients such as lipids and fats. Gorillas find the fruit itself to be their favorite part of the plant. Lastly, bees thoroughly enjoy the nectar of the flower and find it necessary in their production of honey  (Ainge & Brown, 2001).

That being said, insects are the most important pollinator of this plant. The plant itself flowers twice a year, so there is plenty of time for pollination season. There are two obvious peaks of flowering, the height of the dry season in January, and the wet season in October  (Ainge & Brown, 2001). 

However, the fruiting time of this plant is less variable, with there being a range of fruiting twice a year, in accordance with the flowering times, all the way to slowing down to fruiting once every two years (Ainge & Brown, 2001). However, the trees begin flowering after reaching maturity. This usually takes about ten to fifteen years, but sometimes they can begin to bloom as early as six years old  (Ainge & Brown, 2001).

Morphological Description of Vegetative Attributes

In general, this species is very large. They grow up to 40 meters tall, and have a meter wide buttresses that grow to nearly 3 meters high  (PROTA4U, 2017). The bark  is scaly and heartwood soft,  with both being a green-yellow to gray. Also, the inner bark is fibrous and of an intense yellow  (PROTA4U, 2017). Not only are there different textures throughout the wood, it is also quite dense, making them prone to shrinkage.The leaves themselves are simple, elliptical, leathery, thin, pinnately veined,  and alternate up the stem  (PROTA4U, 2017). 

 

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