Flower–leaf sequence shapes plant phenological sensitivity to warming

Plants coordinate reproductive and vegetative development through specific flower–leaf sequences, traditionally viewed as fixed species traits. Yet, as climate warming reshapes plant phenology, the variability of flower–leaf sequence and its impact on phenological responses to temperature change requires re-evaluation. Here, using 40 years of 3090 phenological sequences from 80 woody species across Eastern China, we found that 70 species have both flower-first and leaf-first records. The proportion of flower-first records increased with latitude and over time. Reproductive phenology in flower-first plants was considerably more temperature sensitive than in leaf-first plants. For example, flower budburst advanced by 2.38 days/°C in flower-first plants compared to 1.86 days/°C in leaf-first plants, with similar trends observed for inflorescence emergence, flowering and fruit development. In contrast, vegetative events showed convergent responses between the two sequences. Synthesis. Our results reveal an unexpectedly high degree of variability in the flower–leaf sequence. This variability is crucial in shaping plant responses to warming, particularly in reproductive phenology. Therefore, to accurately evaluate temperature responses of reproductive phenology, it is essential to analyse flower-first and leaf-first plants separately, even within the same species.