Defending Your Roots

Photo by Bobby Watson — An acacia-ant patrols the top of the bull's horn thorn on an ant-acacia tree.

The flora in the forests of Costa Rica can be very inviting. Species of Fern seem to wave hello as you pass them on the trail, and Strangler Figs embrace you in their hollow core.

Some native plant species however are not as welcoming. As you reach down to the forest floor to inspect the tiny Sensitive Mimosa, you can easily see where it gets its appropriate name. The faint touch of a fingertip on its outer leaves causes the shy plant to immediately collapse on top of itself. This reaction protects the plant’s fragile structure from harm.

Plants like these have developed physical defense mechanisms to shelter them from other organisms who eat them and compete for their nutrients.

The Jabillo tree is another prime example of evolutionary plant adaptation. The trunk of this intimidating tree is reminiscent of a medieval weapon, complete with sharp spikes that extend from top to bottom.  The Jabillo has displayed these features since prehistoric times to prevent megafauna (for example cow-sized relatives of the armadillo) from climbing its branches.

Photo by Bobby Watson — The thorns of the Jabillo tree stand guard against now extinct megafauna that would try to scale its trunk to reach leaves higher up.

Perhaps the most interesting form of defense seen by Costa Rican flora is the mutually beneficial relationship between the acacia-ant and the ant-acacia tree. The ant aggressively protects the plant from hungry herbivores, and prevents encroaching plants from robbing it of nutrients and space. In return the ant-acacia tree provides the ants within nourishment in the form of nectar from its leaves and protein-rich Beltian bodies that protrude from its tips.

The defensive strategies exhibited by these plants couldn’t be more effective if they were designed by seasoned military specialists. The plant identifies its predators, adapts over time and protects itself. These strategic methods of survival in a biologically diverse environment allow the plants to grow and flourish in the forest.

— Nikki Barr

2 thoughts on “Defending Your Roots

  1. Debbie Allen says:

    This relationship in nature is fascinating. I enjoyed reading your story.

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