Mexico is one of the 12 megadiverse countries that together contain about half of the world's biodiversity. Specifically, nearly 10% of known vascular plant species can be found in Mexico, owing to its intricate topography that leads to numerous microenvironments, and to the convergence of Nearctic and Neotropical biotas in this country (Neyra González & Durand Smith, 1998). A corresponding botanical knowledge has also emerged in Mexico throughout its history, contributing with the domestication of universally important plants such as bean, cacao, maize and tomato. Unfortunately, the southern Mexican states, which are the most biodiverse, are the ones facing the nation's highest rates of deforestation and the gravest hindering of socioeconomic development. Thus, a pressing need for understanding the mechanisms leading to species persistence emerges simultaneously with an urgency to implement management practices that make conservation compatible with development. In this context, the XVI National Botanical Congress considered the ‘scientific and conservation challenges in a megadiverse country’. Some examples of how environmental physiology can address such challenges were discussed during the symposium.