Between 20 and 33% of the world's plant species are currently at risk of global extinction. That's the estimation of recently published studies. So how much will climate change impact on the variety, availability and price of the food on our plates? Botanist James Wong investigates the links between global warming and the rate at which crops are able to adapt and evolve to rapidly changing conditions.

Speaking to farmers, plant breeders and scientists at the Royal Botanic Gardens, Kew and elsewhere he hears about the plant world's likely 'winners' and 'losers'. Having deeper roots and more efficient water-use strategies is a clear bonus, and one that's being addressed by British plant scientists who are developing more drought-resistant wheat varieties by breeding them with ancient antecedents of one of the world's most important crops. That's in the UK, but elsewhere around the world, James Wong learns that many plants are facing extinction before they have been recognised as being at risk, and perhaps in some cases even before they have been discovered.

Producer: Mark Smalley.