From the University of Michigan Dept. of Pathology:
Every Pathology lab uses the routine Hematoxylin and Eosin (H&E) stain for screening samples in anatomic pathology. It is one of the oldest stains, with some hematoxylin staining protocols dating back over a hundred years. Little do most people know that hematoxylin is a natural product from the legume logwood tree (Haematoxylum campechianum). The history of logwood is a fascinating story as this tree played a surprisingly exciting role in the early history of the New World, where it’s great economic importance helped to build nations and made it a coveted commodity of pirates in the Atlantic.