Introduction
Rubiaceae
Asclepiadaceae
Nepenthaceae
Bromeliaceae
Orchidaceae
Polypodiaceae
Ecology and
evolution
Cultivation
References
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Asclepiadaceae
Several species of Hoya and Dischidia, epiphytic members of
the
milkweed family, house ant colonies in or under their leavess.
Hoya is best known for Hoya carnosa, the waxvine, which is a popular houseplant.
A less well known myrmecophytic species is Hoya imbricata. In Hoya imbricata, one of each leaf-pair atrophies, and the other develops into a convex plate, tightly hugging the bark. Ants live in the space under the leaf. The myrmecophytic species in the genus Dischidia have three different types of ant leaves (Rintz, 1980). The simplest form, found in species such as D. collyris is very similar to the plate-like ant-leaf of Hoya imbricata. More complex are the pitcher leaves of Dischidia major (syn. D. rafflesiana). In this species, the developing leaf folds down to form a chamber shaped like a large pickle. The most complex ant leaves, like those of Dischidia pectenoides, have
an additional inner chamber formed by the folded tip of the leaf.
In the pitcher-leaf species of Dischidia, roots
grow down the petiole and into the hollow leaf. Based on the
observation that root growth into the leaves is more luxurient
in the presence of ant debris dumps, it was proposed that D. major is
an ant-fed ant plant (Janzen, 1984). Analysis of carbon and nitrogen isotopes
in Dischida leaves later confirmed that the plants obtained nutrients from the
debris (Treseder et al., 1995).
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