dimanche 10 février 2013

Strange fruit

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Myrmecodia (Myrmekodes in Greek= full of ants) is a interesting genus of 26 species of epiphytic ant plants native to South-East Asia, where they grow on branches of rain forest trees. The plants develop a spiny greyish caudex to store water and food.
These plants form symbiotic relationships with mycorrhizal fungi and ants, which allows them to obtain sufficient nutrients, despite a very limited root system and minimal substrate. The caudex develops a labyrinth of internal chambers opening to the surface and inviting occupation by ants.

Myrmecodia beccarii (family Rubiaceae) has a swollen body that contains galleries ("domatia" in biological terminology) where the ants live. The only function of these holes is to serve as a shelter for ant colonies. In these plants, there are openings or thin windows of tissue which enable ants to get in and out of the plant easily. In these chambers, there are food bodies that the plant produces with no known function other than the feeding of ants.

They do not appear to have a real use for the plant.9 In short, domatia are very special structures that have been created in order for ants to live. The heat and moisture balance provides an ideal environment for ants. In these places marked by diligence that are prepared for ants, the ants make themselves just as comfortable as people staying at luxury hotels.

 

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Dischidia is a family of epiphytes from SE Asia and Australasia. It is closely related to Hoya although it is vegetatively a much smaller plant and the flowers are usually not showy.
The plant has no roots penetrating the soil (epiphytes), most epiphytes gets carbon and nitrogen from air. But Deschi get it from ants (mostly Philidris). Ants breed their offspring and store organic remains (dead ants, pieces of other insects, etc.) inside the "ant-leave". The plant makes use of these residues as a nitrogen source. Moreover, the inner surface of the leaf spaces absorbs the carbon dioxide given out by the ant, and in the process decreases dehydration through pores.10 Preventing dehydration is very important for these ant plants which grow in the tropical climates, because, they have no roots and cannot reach water in the soil. So, ants supply two important needs of the plants in return for the shelter provided to them.Almost all of the species of Dischidia have close relationship with ants and many have evolved interesting vegetative aspects to attract ants.

They are some with pouch leaves where ants can build nests within, another type have disk shaped leaves pressing against the trunk which again act as ant shelter. Two other types of Dischidia are not designed to attract ants (although they usually are found around the aerial ant nests), having either flat thick leaves (as in D. hirsuta) or bearing small knob-like leaves along very long internodes (eg D. bengalensis). Researchers have trace the movement of radioactive carbon and nitrogen atoms from ants to plants, confirming that the plants assimilate matters brought in by the ants.

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