What vine is potted by ants?
By Chelsie Vandaveer
October 17, 2002
Dischidia rafflesiana Wall [dis shid' ee a ra fleas' ee ana] is a strange member of the Asclepiadaceae or milkweed family. This twining vine is native to Borneo, Australia, and India.
Dischidia rafflesiana leaves are dimorphic (having two distinct forms). Most of the leaves along the vine are small, pale green, and somewhat heart-shaped. At odd distances along the vine, the plant grows large inflated leaves frequently in a cluster. The vine at these points roots to the surface of its support. It also sends roots into its own leaves.
Dischidia rafflesiana's hollow leaves are domatia; they encourage ants to inhabit. Bert Hölldobler and Edward O. Wilson propose the plants are myrmecotrophic (ant 'fed'). "The flask- and bladder-like domatia of Dischidia, for example, are penetrated by networks of adventitious roots that almost certainly absorb nutrients. Crematogaster and other ants that live and accumulate organic detritus on these roots are in fact literally "potting" the Dischidia." (The Ants, 1990)
The ants' trash becomes the Dischidia's potting soil. Rainwater, trapped in the hollow leaf, further aids the vine's upward growth. Eventually the older portions of the Dischidia die and it is no longer in contact with the ground. The 'nutrient pots' allow the plant to continue growing indefinitely as an epiphyte.
Peter v. Sengbusch of the Biology Department, University of Hamburg has great photographs and a detailed drawing of Dischidia rafflesiana. To view the photographs, click on the link:
http://www.biologie.uni-hamburg.de/b-online/d52/dischid.htm
|
