Algae can get energy from other plants, researchers from Bielefeld University have found. Conventional wisdom held that plants get energy only from the sun.

The one-celled alga _Chlamydomonas reinhardtii _ breaks down plant cell walls into sugars when starved of carbon dioxide. Until now this behaviour had only been seen in animals and fungi.

The algae could be used to make biofuel from plant waste.