In 1947 an ambitious project began to survey and catalogue the biodiversity of plants in East Africa. It was to take 60 years and turned out to be one of the largest regional "floras" ever assembled, involving 135 botanists from 21 countries amassing a host of new species to science.

Professor Kathy Willis examines the deceptive simplicity of creating Floras - books in which plants are catalogued, described and often lavishly illustrated. She explores how they're proving powerful tools for unlocking the range of newly discovered species for plant enthusiasts and conservationists.

And she unlocks the secrets of the rigorous art of botanical illustration, a tradition that goes back as far as when the botanical impresario Sir Joseph Banks first employed an illustrator on board the Endeavour. Kathy Willis discovers why this discipline is unlikely to ever be superseded by photography.

With contributions from Henke Beentje, former editor of Flora of Tropical East Africa, senior botanist Iain Darbyshire, Quentin Luke of National Museum of Kenya and illustrator Lucy Smith

Producer: Adrian Washbourne