The Race for Sunlight – Part II: Epiphytes & Parasites

Last month we introduced you to some of the strategies used by plants to overcome the challenges of living in a highly competitive rainforest. This month, we will introduce you to two other strategies used by plants, these are parasitism and epipythism.

Epiphyte Bromeliads – Photo: Steve Winter

Epiphyte Bromeliads – Photo: Steve Winter

Parasitism:

The most common way for an organism to make a living in this world is by being parasitic, in other words, taking advantage of another organism to make a living. This is also true in the world of plant evolution. Several species of plants take advantage of other plants to thrive. The most striking example found in the Amazon Rainforest is the ‘Strangler Fig’. This Fig makes a living by first being deposited as a seed on a high branch of another tree. After this, this fig will start growing roots until it hits the forest floor. Once this happens, the host tree is doomed. The fig will take advantage of the nutrients from the ground and will rapidly grew all around the host tree. After this, the Fig will start to suffocate host tree until it’s dead. What you are left with is a gigantic tree with a hole in the middle (the host tree will decompose after it dies). These cavities are perfect hiding places for a wide array of creatures, specially bats.

Here is a nice video explaining the life cycle of the Strangler Fig:

Epiphytism:

Epiphytes are organisms –typically plants, but it also applies to some fungi, algae, and lichens- that growth in top of another organism. The catch is that this is a commensalistic relationship and not a parasitic one, as it was a case with the Strangler Fig. The difference is that in contrast to the parasitic relationship, the host is not benefited or harmed by the presence of the commensal.

Bromeliads – Photo: Geoff Gallice

Bromeliads – Photo: Geoff Gallice

A great example for this relationship are Bromeliads. Bromeliads use trees –and sometimes prominent rocks, or human infrastructure- as an anchoring place. They live there but do not harm the host on any way. The have what is known as ‘aerial roots’, which with they absorb inorganic nutrients from the air, rather from the soil. Bromeliads are highly prolific on places like Manu, as they need high quantities of rainfall and humidity to survive.

Another example of epiphytism is seen at higher altitudes of Manu Road, specially around the Yungas Forest. Lichens and non-vascular plants (mainly mosses) thrive in this altitude, and it is actually hard to spot a branch which is not fully covered in lichens and mosses.

Hooded Mountain-Tanager – Photo: Geoff Gallice

Hooded Mountain-Tanager – Photo: Geoff Gallice

The following photo, of a Hooded Mountain-tanager shows how densely packed the branches are with mosses and lichens.  

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