Iron (Fe) deficiency severely limits plant growth in calcareous soils. Plants have evolved two main strategies to acquire sparingly available Fe under these conditions. These strategies may show natural variations that can be exploited for agriculture but remain unexplored since most research has focused on crops and model plants. To find such variations, we cultivated various plant species in a high throughput manner under Fe-sufficient and deficient media and compared their Fe deficiency responses. We discovered that Veronica officinalis, a species adapted to non-calcareous soils, failed to induce the accumulation of fluorescent phenolic compounds in roots, a common response to Fe deficiency in several species, when grown in a Fe-deficient medium. On the other hand, Trifolium montanum, a legume adapted to calcareous soils, showed pronounced root fluorescence even when cultivated in a Fe-sufficient medium. T. montanum plants also showed constitutive ferric chelate reductase activity and rhizosphere acidification, indicating a general defect in turning off Fe deficiency-induced responses. These findings suggest that adaptation to contrasting environments with predictable Fe availability can lead to a loss of plasticity in Fe deficiency responses. While V. officinalis benefits by giving up a Fe-acquisition component that is non-essential where it is adapted, T. montanum benefits from constitutive Fe acquisition in chronically Fe-deficient calcareous soils. These contrasting adaptations highlight the trade-offs inherent in maintaining plasticity and underline the importance of studying stress responses in wild species of diverse natural settings, which can contribute to developing stress-tolerant crops.