Gregory De Vries spoke to the integration of culture and nature using historic plant materials as a focus for the Harvard GSD course, led by Charles Birnbaum, FASLA and titled Why not cultural systems? The posited that: The recognition of the intertwined realities of culture and nature, imply that just as physical places change, the ways that they are inhabited and perceived also change over time – meanings shift. Understanding these transitions elicits respect for the origins of both nature and culture in place, which provides the critical context for planning and design intervention and innovation. Often interventions in valued landscapes require integration of historic preservation and ecological restoration. Plants are an important asset of landscape character to address in these works.