The environmental fluctuations of a constantly evolving world can mould a changing context, often unfavourable to sessile organisms that must adjust their resource allocation between both resistance or tolerance mechanisms and growth. Plants bear the fascinating ability to survive and thrive under extreme conditions, a capacity that has always attracted the curiosity of humans, who have discovered and improved species capable of meeting our physiological needs. In this context, plant research has produced a great wealth of knowledge on the responses of plants to a range of abiotic stresses, mostly considering model species and/or controlled conditions. However, there is still minimal comprehension of plant adaptations and acclimations to extreme environments, which cries out for future investigations. In this article, we examined the main advances in understanding the adapted traits fixed through evolution that allowed for plant resistance against abiotic stress in extreme natural ecosystems. Spatio-temporal adaptations from extremophile plant species are described from morpho-anatomical features to physiological function and metabolic pathways adjustments. Considering that metabolism is at the heart of plant adaptations, a focus is given to the study of primary and secondary metabolic adjustments as well as redox metabolism under extreme conditions. This article further casts a critical glance at the main successes in studying extreme environments and examines some of the challenges and opportunities this research offers, especially considering the possible interaction with ecology and metaphenomics.