The history of rhododendrons is full of swashbuckling plant collectors and visionary gardeners, colonial violence and ecological destruction, stunning botanical successes and bitter business disappointments. And it is here related with consummate skill by Jane Brown, an English garden writer clearly besotted by these glorious and scented strangers, with their mouth-watering candy colors, their cascades of way bells or iridescent globes proffered in ruffs of green leaves.