The world’s oldest fossilised forest was uncovered in Somerset last week. We head to palaeobotanist, Dr Christopher Berry’s, lab at Cardiff University to learn about these cladoxylopsids. They lived 390 million years ago and although they are not the ancestors of today’s trees, they reveal some extraordinary evolutionary secrets.

Also, Marnie speaks to Dr Chris Thorogood of the University of Oxford Botanic Gardens about his new book Pathless Forest: The Quest to Save the World’s Largest Flowers. Called “Rafflesia” plants and found in the remotest parts of South East Asia, their flowers burst from the rain forest floor the size of pumpkins and are critically endangered. Chris talks of his world of extreme fieldwork and hair-raising expeditions, braving leeches, lizards and lethal forest swamps, to discover the rarest of rare blooms.

Plus, the Wildlife Trust’s Making Friends with Molluscs campaign starts today, and I’m sure many gardeners will declare this an impossible task! We visit some allotments in Bristol to find out how people are managing slug and snail populations. And chat to Brian Eversham from the Trust of Bedfordshire, Cambridgeshire and Northamptonshire, who explains why these garden creatures should be considered our friends, not foes.

And finally, Dr Stewart Husband from last week’s programme returns to answer more of your burning questions about your tap water.