“The best gardeners of my generation are not hybridizing roses, are not working with orchids. They are working with this incredibly valuable and incredibly interesting plant called cannabis.” --Michael Pollan Before Michael Pollan’s best-selling books about food and the food industry, he wrote a fascinating volume about humanity’s symbiotic relationship with plants, called “The Botany of Desire.” That book is now a PBS special, airing for the first time this week, on October 28 at 8 p.m. If you have…