The origin of the word biomagnetism is unclear, but seems to have appeared several hundred years ago, linked to the expression animal magnetism. The present scientific definition took form in the 1970s, when an increasing number of researchers began to measure the magnetic fields produced by the human body. The first valid measurement was actually made in 1963. Now plant biomagnetism has been little studied. Searching for magnetic fields produced by plants may sound strange, but physicists at the University of California, Berkeley, are seriously looking for biomagnetism in plants using some of the most sensitive magnetic detectors available.