Background/Question/Methods Phenological shift is the most commonly used indicator of Climate Change impacts on population and ecosystem level patterns. Based on these patterns, several concerns have been raised about the effects of these changes on population and ecosystem level processes, but the necessary causal links from warmer temperatures, via phenological shifts to disruptive changes at population and ecosystem levels are in most cases non-trivial. Trophic, mutualistic, competitive, and facilitatie interactions may indeed include timing as an important factor. The annual life cycle often includes temporally, tightly coupled phases. Timing of any of these phases may also be linked to other traits through evolutionary trade-offs. Still, background, inter-annual variation in climate is large, and claims that Climate Change driven phenological shifts will have significant effects on population abundance, plant distribution, and ecosystem properties, must therefore be based on site- and organism-specific, and process-oriented data. These issues will be discussed using two unique approaches: First, a 73-year long, temporally unbroken flowering onset time data set for 25 species is used to explore the diversity of responses to Climate Change. Second, I explore latitudinal, inter-annual, and phylogenetic patterns of flowering time, as well as phylogenetic patterns in Climate Change driven change in flowering time. Results/Conclusions Strong correlations were found between mean flowering onset time and both latitudinal and inter-annual variation in flowering time. Also, there was a strong phylogenetic signal in flowering time per se, but no significant phylogenetic signal for change in flowering time. In relation to these results, I discuss the idea that those plant lineages that experience the largest phenological shifts may be those that also possess adaptations suited for mitigating these effects.