Plants and bees The relationship between flowering plants and bees is a long-evolved, complex one. Plant scientists at the Royal Botanic Gardens at Kew are currently conducting field trials to see how Acontium, or Monkshood, uses toxins to protect itself against nectar-thieving, short-tongued bumblebees. But how does it make sure it doesn't poison the helpful, pollinating long-tongued bumblebees? Plants from Roots to Riches Professor Kathy Willis, Director of Science at the Royal Botanic Gardens Kew will be presenting a new series on BBC Radio 4 exploring our relationship with plants from the birth of botany through to modern day. She describes some of the series highlights. The Azolla Event A tiny ancient fern-like pond weed could have been responsible for changing the fate of the planet. Some scientists think that Azolla could have played a significant role in reversing an increase in the greenhouse effect that occurred 55 million years ago. The researchers claim that massive patches of Azolla growing on the (then) freshwater surface of the Arctic Ocean consumed enough carbon dioxide from the atmosphere for the global greenhouse effect to decline, eventually causing the formation of ice sheets in Antarctica and the current "Icehouse period" which we are still in. Chomping caterpillars Plants can hear. Well, they can sense sound-vibrations. New research from the University of Missouri shows that when the mustard-like Arabidopsis senses the chomping sounds of a caterpillar munching on leaves, it primes itself for a chemical response. Composting low down A listener asks why orange peel takes so long to rot down in the compost heap? Is it because it's an exotic fruit? Adam asks Kew's Head of Horticulture and 'keeper of the heap' Dave Barns. Producer: Fiona Roberts.