Carol Klein's Plant Odysseys S01E01 - Roses

The first episode looks at the rose. 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.

Roses are loved for their perfume as much as their beauty, but the scent a rose produces is not for our benefit. Professor Geoff Ollerton explains where in the flower the wonderful smells originate and how odour plumes spread in order to entice passing pollinating insects. These aren't the only chemical messages that the rose can broadcast. When under aphid attack, they release an aroma that acts like a distress beacon to summon in ladybirds and other insects for an aphid meal.

The rose has come to be so much more than just a collection of cells and chemical reactions. At Exeter Cathedral, Carol sees what an important symbol it has been to religion, and we discover that a chance meeting in the 18th century between two roses on the Island of Reunion created a whole new class of rose - one that would lead to a passion for breeding the exquisite, voluptuous blooms that we know and love today.