In 1903 a cluster of evening primrose in an abandoned potato field outside the Dutch town of Hilversum caught the eye of German botanist Hugo de Vries. Its huge blooms and large leaves appeared to suggest the sudden development of a new species. Around the same time in Kew Gardens a mysterious primula hybrid appeared. The new discipline of plant genetics soon revealed that this curious trick was being driven by multiplication of chromosomes inside the plant cell nucleus. Professor Kathy Willis examines this phenomenon - known as polyploidy ( "multiple forms") - and how insights into this peculiarity can contribute to the evolutionary success of plants. It may also hold the answer to one of the botanical world's greatest mysteries - why so soon after appearing in the fossil record did the flowering plants suddenly explode into the bewildering range of species we see today. With contributions from historian Jim Endersby, Keeper of Kew's Jodrell Lab Mark Chase, and Jodrell Laboratory geneticist Illia Leitch. Producer Adrian Washbourne.