Biologist and plant scientist Paul Mankiewicz explains the Gaia Hypothesis, the inherent environmental productivity of organisms, and why the city's waste stream is our greatest untapped ecological and economic asset.

Landscape designer David Seiter champions the ecological and aesthetic benefits of informal plants - weeds - in urban space, and catalogues the uses and cultural significance of New York's native flora.

Urban designer Kaja Kühl illustrates how to use plants to clean up contaminated sites, a cost-effective way to add productive, healthy land to the City’s environment.