Coffee got its buzz by a different route than tea

@article{Callaway2014CoffeeGI,
  title={Coffee got its buzz by a different route than tea},
  author={Ewen Callaway},
  journal={Nature},
  year={2014}
}
Genome of the robusta variety reveals that caffeine-making evolved more than once. 

References

The coffee genome provides insight into the convergent evolution of caffeine biosynthesis
TLDR
The Coffea canephora (coffee) genome was sequenced and identified a conserved gene order, and comparative analyses of caffeine NMTs demonstrate that these genes expanded through sequential tandem duplications independently of genes from cacao and tea, suggesting that caffeine in eudicots is of polyphyletic origin.