Philippine Deforestation

Ant Plant

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© 2002 (Photograph by A. Vogel)

Plants of many different groups have evolved to attract ants to live with them, providing the ants with food and shelter. In return, the plants receive nutrients from the ants' droppings and protection from plant-eating animals.

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Perhaps the most peculiar plants in the Philippines are those that play host to ants: such flowering plants as Myrmecodia, Hydnophytum, Hoya, and Dischidia, and ferns including Lecanopteris and Phymatodes. The bases of the stems of Hydnophytum and Myrmecodia are greatly enlarged and honeycombed with tunnels through which an army of small ants transports food. The ants benefit from the shelter provided by the plant, while the plant gets part of its nutrition from the organic detritus left by the ants. The ants may also drive away other animals that would otherwise eat the plant.
Hoya and Dischidia are vines with milky sap belonging to the milkweed family. In some species of Hoya, the dome-shaped leaves grow very close to the bark of the tree-trunks to which they cling. Each leaf extends many roots, holding the plant in place and absorbing moisture and nourishment from the nests of the ants that make their homes under the dome-leaves. On the other hand, some species of Dischidia produce two types of leaves: one small, the other greatly swollen and hollow. The latter collect water and provide homes for the ants. Roots extend from the stem into the hollow spaces in the leaves to absorb moisture and nutrients left by the ants.
Phymatodes and Lecanopteris are strange-looking ferns whose swollen, hollow rhizomes are inhabited by ants. Phymatodes sinuosa is a lowland species that grows only in the canopy, its thick, scaly rhizomes creeping along the branches of trees in moderately exposed places. At elevations higher than 1,000 meters, the strange Lecanopteris carnosa appears to be more common. Its rhizomes are green and pale blue-green when young, but turn black and horny with age. The young rhizomes form a thick crust around the branches of trees. Ants build nests in the safety of these elevated rhizomes. Small orchids and other plants often grow in the rhizome's crevices, germinating from seeds deposited by the ants and contributing to the development of tiny plant communities on tree branches high above the forest floor.

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