Abstract
The past 25 years have seen remarkable progress in plant circadian biology. This perspective highlights major advances in our understanding of the oscillator network, the processes it regulates, and circadian variation across tissues and cell types. Genomic and systems approaches uncovered pervasive circadian control of physiology, development, and fitness, including photoperiodic and domestication traits. Emerging tools now position the field to engineer clocks for agricultural resilience in a changing climate.