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Australian native plants are remarkably tolerant to a wide range of environmental conditions in which they grow. However, as the climate changes, background warming and extreme climatic events are pushing plants closer to their limits. The heat tolerance of important crops has been well-studied using many types of measurements, but what do we know of heat tolerance in our diverse native plants? How tolerant (or sensitive) are they to increasing heat load and can they adjust their physiology through plasticity to better cope with heat? What consequences are there for function and fitness? I will highlight what we have learned from several research projects based in the field, glasshouses, and laboratory. Then I will introduce an extended theoretical framework called Thermal Load Sensitivity that can be applied across life forms – plants and animals alike. This framework was developed to model the dynamic processes of damage and repair over time during periods of heat with and without reprieves to allow recovery of function based on sublethal measures of tolerance. Our current empirical research aims to use this framework to study the sensitivity of different life stages and tissue types to heat, to better understand impacts of heat across entire life cycles.