The study of plant intelligence is one of the most fascinating fields of modern science. A little while ago, I wrote about a study which showed that plants hear the sounds of pollinating animals and can actually respond with their own subliminal (to humans) sounds. Now a another study has shown that the relationship between plants and pollinator can be even more dynamic. A study of Nasa poissoniana, a Peruvian flower in the Loasaceae family found high in the Andes mountains, has found that these colorful, star shaped flowers actually build memories of their pollinator friends and move their stamens—the reproductive organs of the flower that get the pollen to the pollinator—in anticipation of what those pollinators will do.
The study, published in the journal Plant Signaling and Behavior, looked at how the behavior of the flowers changed depending on the intervals between pollinator visitation. Loasoidae flowers are special in how much "behavior" they can exhibit. While many plants show some sort of movement—curling their leaves or closing their flowers— Loasaceae flowers can swing their stamens around their flowers to maximize pollen distribution.
The stamens of Nasa poissoniana look like long, white whiskers capped with pollen, tucked in with the flower's petals. Over the course of the flower's life, it moves its stamens one at at a time into the center of the flower to present pollen to visiting pollinators like bees. The movement of the stamen takes only three minutes, which is the plant equivalent of an Olympic sprinter, and it was this predilection towards triggered movement—or "thigmonasty"—that interested the researchers in Nasa poissoniana.
The study involved groups of humans artificially pollinating three separate groups of Nasa poissoniana at regular but different intervals over the course of one day. One group of flowers was pollinated every 15 minutes, another every 45, and the final group was left alone as a control. A day later, the researchers observed the behavior of the flowers and found that they seemed to remember their pollination schedule from the previous day. The group that had been pollinated every 15 minutes moved their stamens around quickly, anticipating a quick turnover on pollination. Their pollen concentrations peaked at 15 minute intervals. The 45-minute group was slower and lazier, but still accustomed to what they had been trained to expect. Their pollen concentrations peaked at 45 minute intervals.
Dr Tilo Henning, one of the study's lead authors, says the plants were "anticipating pollinator revisits" and expects that other members of the Loasaceae family are capable of similar anticipation. Dr Henning says that the results of the study are curious:
“The tremendous overall expenditure these plants invest in spreading their pollen around is puzzling.There are a number of similar successful plant groups. But none of them shows such an elaborate effort.”
Plants seem to become more puzzling by the day. While it certainly isn't evidence of the type of memory that you and I have, this study is more evidence that plants don't simply grow, but dynamically act and react with their environment. So think about that the next time you make yourself a salad, you monster.