Tropical plants are hot attractions.

Tropical plants are hot attractions

Flowers are considered pleasing because the elaborate reproductive structures and mechanisms they have evolved are often pretty and sweet-smelling. Less appreciated is the reproductive strategy of literally heating up, used by hundreds of plant species to help attract pollinating insects. While studying the complex insect ecology taking place in these plants deep in the forests of Costa Rica, graduate student Lloyd Goldwasser of the University of California at Berkeley may have identified the masters of this hot strategy.

Goldwasser observed that the flower stalks of seven species in the Araceae family, including philodendrons and "elephant ears," can heat up to more than 105[deg.] F at dusk the day before they release pollen. Within an hour, the temperature of the stalks rockets by more than 40[deg.] F and then peaks for about 30 minutes before cooling down to the ambient 60[deg.] to 65[deg.] F by about 10 p.m. When the stalks heat up, they broadcast a "vivid, sweet aroma" that Goldwasser says he was able to smell from as far as a football field away. He says the flower stalks reached 105[deg.] F even when he cut them off and put them in a refrigerator.

Scarab beetles, which wing about also at dusk, home in on the aromatic stalks and spend the nigh there eating and mating. At pollen-releasing time, approximately 24 hours later, the flower stalks heat up to about 90[deg.] F and the beetles fly away with cargoes of pollen grains in their guts and on their bodies.