Plant of the Week: Ficus aurea

Ficus aurea, also known as the Florida strangler fig, is in the family Moraceae, which includes cultivated plants such as mulberry and breadfruit. The genus Ficus includes species such as the common fig, Ficus carica, and strangler figs (e.g. Ficus watkinsiana and Ficus altissima) [1].

ficus-aurea-e1522779787153.jpg
Edited from Useful Tropical Plants – Ficus aurea

Adaptation

Strangler figs are a group of plants found in the tropics and subtropics that grow through strangling a host plant. All species of strangler fig are classified within the genus Ficus but there are other strangler species (e.g. within the families Araliaceae and Clusiaceae). In David Attenborough’s The Private Life of Plants series, he entertainingly describes how a strangler fig consumes another plant.

Briefly, a seed, likely dispersed by bird, germinates in a crevice at the top of a host tree. Once established, the roots begin to grow downward towards the ground to obtain nutrients, not only from the host but the surrounding environment. As the roots develop, the plant begins to grow reducing the amount of sunlight reaching the host species. The roots slowly constrain plant growth, “strangling” the host species. Often upon completion of this process, the strangled tree dies. However, having developed an intricate network of roots, the strangler fig is able to support itself.

This evolutionary adaptation is termed a hemiephiphytic life cycle. An epiphyte is an organism that grows on the surface of a plant and therefore a hemiepiphyte is an organism that spends part of its life cycle as an epiphyte [2]. Epiphytic plants common to the tropics that I plan to discuss in future posts include many species in the families Orchidaceae and Bromeliaceae. There are also terms for an organism that grow on another life form, plant or otherwise (epibiont) or grow on a rock (epilith).

Distribution and characteristics

Ficus aurea is native to Central America with its range spanning from the state of Florida to Panama. It can be found in tropical forests and aquatic habitats and can grow between 30 to 100m in height. It is pollinated solely by fig wasps in the family Agaonidae. These mutualistic partners of the fig tree are defined as obligate, meaning that neither species can survive without the presence of the other. The strangler figs cannot be pollinated by any other insect whilst the fig wasp is only able to reproduce within the flowers of the strangler fig [3].

Why is it Plant of the Week?

The lifestyle of Ficus aurea as an epiphyte makes it an interesting plant. Alongside this fascinating strategy, the Florida strangler fig is used in agriculture as a building material in Central America [4]. It has also been utilised as an ornamental tree and tamed to produce bonsai forms. I feel that the relationship between the strangler fig and its host species demonstrates that plant biology is not static or simple but that the ecological interactions of flora with their surroundings is an ever changing, dynamic continuum.

If you want to learn more:

  1. Zhou, Z. & Gilbert, M, G. 2003. Flora of China (Moraceae) 5: 21-73.
  2. Putz, F. E. & Holbrook, N. M. 1989. Strangler Fig Rooting Habits and Nutrient Relations in the Llanos of Venezuela. American Journal of Botany. 76(6): 781-788.
  3. Bronstein, J. L. & Patel, A. 1992. Causes and Consequences of Within-Tree Phenological Patterns in the Florida Strangling Fig, Ficus aurea (Moraceae). American Journal of Botany. 79(1): 41-48.
  4. Harvey, C. A. & Haber, W. A. (1998). Remnant trees and the conservation of biodiversity in Costa Rican pastures. Agroforestry Systems44 (1): 37–68.

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