It's common knowledge that some animals can detect and use Earth's magnetic field, but now Italian researchers have identified a possible mechanism by which plants might react to it as well.
The researchers even ponder the possibility that surges of plant evolution in Earth's history -- especially the appearance and spread of flowering plants -- might match times when the Earth's flip-flopping magnetic poles were like that of today.
"Compared to studies in animals, very little is known about magneto-reception in plants, although early studies on plants were initiated more than 70 years ago," explains the University of Turin's Andrea Occhipinti and colleagues in a paper in the January issue of the journal Trends in Plant Science.
There have been studies that suggest that plants do, indeed, respond to both strong and weak magnetic fields, but the experiments have been hard to duplicate, leaving a lot of questions still unanswered, the researchers wrote.
In birds the trick to detecting magnetic fields is the existence of a blue-light receptor protein, called a cryptochrome, in the birds' eyes. Cryptochromes are thought to be activated by light, and then they become sensitive to a magnetic field.
Oddly enough, the same protein has been found in plants, where, theoretically, they might also enable plants to react to magnetic fields. The big question, of course, is what use would a plant have for this extra ability? After all, plants don't migrate.
"Plants probably don't sense the Earth's magnetic field," said physicist Ilia A. Solov'yov of the University of Southern Denmark. Solov'yov has done work on cryptochromes, which are actually very common and exist in humans as well, he said.
"The fact that they have cryptochromes is probably an artifact in the same way that people have them," Solov'yov said, without the ability to use them to navigate. Evolution leaves relics behind -- think of your appendix, little toe or wisdom teeth – which sometimes find new uses, gradually disappear, or mysteriously stick around.