Orchids are big business. Today over £5m of orchid hybrids are imported as cut flowers into the UK each year. For the Victorians orchids were the chosen ornaments of royalty and captured the 19th century fascination with scientific oddity and imperial conquest. Prof Kathy Willis explores how orchids, one of the planet's most diverse family of plants, mesmerised Victorian devotees and became not only trophy plants of the rich but also a scientific tool to promote a new theory of evolution. The study of orchids also paved the way for cultivation of exotics for all. Lara Jewitt tours the orchid glasshouses at Kew where over 3000 species are cultivated, and explains the biology unique to orchids that fuels interest for both scientists and plant lovers. Darwin was fascinated with these rare and precious plants. Their unique pollination mechanisms helped back up his new evolutionary theory based upon natural selection. As historian Jim Endersby reveals, the delicate orchid was to play a part in getting botany a seat at the top table of scientific respectability. Even in the 1850s, Kew's director Joseph Hooker had expressed concern about the damage orchid hunters were inflicting on the wild population. Whilst today many species remain endangered, V Sarasan, head of Kew's Conservation Biotechnology Unit, reveals how new conservation efforts in some of the most orchid species-rich areas of Madagascar are helping to successfully reintroduce endangered members of this vast but vulnerable flowering family back into the wild. Producer Adrian Washbourne.