In Prospect Park alone, at least 90 species of native bees flit from flower to flower among the park's sun-dappled golden rod, dandelions and dogwood.

WSJ: New Sweat Bee Generates Buzz

In London alone, Reynolds has led dozens of covert digs with hundreds of flower-empowered followers to transform derelict dirt on street corners, roadways and roundabouts into places of rediscovered horticultural beauty -- one of his favorite projects, Reynolds says, is a lavender field planted in a once-barren median on Westminster Bridge Road.

CNN: Guerrilla gardeners green their city on secret moonlit missions