Along with colour and scent, electrical fields on flowers can guide bees' search for pollen and nectar.

Credit: DANIEL ROBERT/DOMINIC CLARKE

Flowers often have a negative charge, whereas insects such as bumblebees (Bombus terrestris) tend to build up a positive charge as they fly. Daniel Robert and his colleagues at the University of Bristol, UK, placed electrodes in stems of petunias (Petunia integrifolia) and found that visits from bumblebees changed the flowers' electrical potential for a short time. The bees could sense such electrical cues and use them to recognize and remember which flowers provided them with a reward. Coating the flowers with coloured, charged particles (pictured) showed that the floral electrical fields were strongest at the outer edges of petals.

Electrical signals could be a particularly versatile way for plants and pollinators to communicate, the authors say.

Science http://dx.doi.org/10.1126/science.1230883 (2013)