Abstract: Climate change is causing shifts in the phenology (timing of life events) of many organisms with consequences such as changes in species interactions and community composition. Owing to the large elevational and latitudinal gradients in its distribution, the native California wildflower, Streptanthus tortuosus (shield-leaf jewel flower) is a great model organism for studying the impacts of climate change. Few studies have have looked at inter-annual changes in climate variables like snowpack and climatic water deficit and their impacts on flowering phenology. Changes in flowering duration due to climate change have also been similarly understudied. Herbarium specimens and local historical weather data were used to make inferences about the impacts of climate variables on flowering phenology and duration. Long-term increases in spring temperatures have led to significant advances in flowering timing. Similarly, long-term decreases in spring snow pack has also advanced flowering timing. Drought-caused increases in climatic water deficit are also causing significant delays in flowering. The duration of flowering has also increased over time. Taken together, these results suggest that climate change is likely causing shifts in the reproductive phenology of S. tortuosus. Understanding these impacts will enable us to better understand and predict the plant’s ability to adapt and persist in California as it faces new and increasingly variable environmental conditions in the future.
