Plants can suffer 'jetlag' if their internal clocks are disturbed

Like other organisms, plants have an internal clock. If their day-and-night biorhythm is disturbed, they might have trouble growing. Photo: dpa

People and animals quite obviously have a biorhythm that dictates when they should, for example, eat or sleep. But even though it's not as noticeable, plants also have their own internal clocks.

A plant's biorhythm, which regulates things such as when it should open or close its flowers, is influenced by sunlight. They know that it's night or day based on their sugar levels, explains Frank Werner from the German Ornamental Plants Association.