Rare flower needs prickly neighbors

In a newly discovered twist on the importance of good neighbors, a member of the mallow family makes more fruit when it grows beside a tangle of pandanus plants.

Researchers had been studying pollination of Trochetia blackburniana, a rare plant found only on the island of Mauritius. Geckos of the species Phelsuma cepediana transfer pollen as they poke their heads into the plants’ large red flowers to sip nectar. When Dennis Hansen of the University of Zurich and his colleagues recently caged the plants to keep away geckos, the plants were less successful in making fruit.

Hansen and his colleagues also found that the Trochetia flowers were nearly twice as likely to form fruit when located near a tangle of pandanus plants. Growing widely throughout the tropics, these small trees form dense clusters of long bladelike leaves.

The P. cepediana geckos forage during the day, when many predators are also active. The dense pandanus clusters could be providing valuable hiding places for them, Hansen and his colleagues argue in the April American Naturalist. Hansen says, “Who would have thought that to conserve Trochetia blackburniana we would end up saying ‘Plant more patches of pandanus’?”

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.