One possible function in plants, suggests Occhipinti, could be to help plants react to elements in soils that are affected by magnetic fields, like some forms of calcium. For now, there are more questions than answers, according to Occhipinti.
"Why should plants regulate their physiological processes in response to variation of (the global magnetic field)? How does (the magnetic field) affect plant development, and do cryptochrome-related biophysical mechanisms play a role in plant magnetoreception?" Occhipinti asks.
And what about changes in the Earth's magnetic field? Do they have anything to do with plant evolution?
"Some authors have pointed out that, during geomagnetic reversals, (life) is exposed to more intense cosmic radiation and/or UV light," Occhipinti said. That could theoretically cause more damage to genetic material, which causes more mutations which, in turn, could speed up the rate at which new species cold evolve.
Occhipinti's team looked at the Earth's magnetic history and reported what they say is just such a pattern in flowering plants (angiosperms) which first came into being about 136 million years ago.
They found that during periods when Earth's magnetic field was like today (when the compass points north instead of south) there appear to have been more new families of angiosperms evolving than during reversed magnetic fields.
"This correlation appears to be particularly relevant for angiosperms compared to other plants," Occhipinti points out. Of course, other factors could explain this, such as global climate changes, or the rise of grasses as the dominant plants, which has been linked to global cooling and drying.
The bottom line, says Occhipinti, is that Earth's magnetic field and magneto-reception might be a relevant factor in plant evolution -- so it's worth investigating.