Virginia Woolf famously began one of her greatest novels: "Mrs Dalloway said she would buy the flowers herself." Of course she would: why would anyone surrender the best part of the day to someone else? Flowers grace our lives at moments of celebration and despair. "We eat, drink, sing, dance, and flirt with them," writes Kakuzo Okakura. Flowers brighten our homes, our parties, and our rituals with incomparable notes of natural beauty, but the "nature"...