Introduction Plant science has never been more important. The growing and increasingly prosperous human population needs abundant safe and nutritious food, shelter, clothes, fibre, and renewable energy, and needs to address the problems generated by climate change, while preserving habitats. These global challenges can only be met in the context of a strong fundamental understanding of plant biology and ecology, and translation of this knowledge into field-based solutions. Plant science is beginning to address these grand challenges, but it is not clear that the full range of challenges facing plant science is known or has been assessed. What questions should the next generation of plant biologists be addressing? To start to answer this question we set out to compile a list of 100 important questions facing plant science research.