Carol Klein's Plant Odyssey s01e01 (2014).

Part 1of4 - Roses.
The rose has always meant so much to Britain - it is embedded in our history, our fairy tales and our hearts. Carol goes on a very British plant odyssey. To understand the origins of our most cherished garden flower, we need look no further than the hedgerow. Our native dog rose - Rosa canina - has changed very little in 37 million years. Its prickles, acting like tiny crampons, allow it to climb above other plants and protect them from being eaten. As a second line of defence, they even harbour bacteria to fend off hungry assailants. The Romans adored its simple flowers, but they adored densely-petalled mutations even more and soon began to develop these by taking cuttings.