The word semplici refers to the raw ingredients, simples, used by medieval apothecaries in preparing medicine -- thus the Giardino dei Semplici was where medicinal herbs were grown and studied.  It was set up in 1545 by Niccolo Tribolo for Cosimo I in the area between Via Micheli, Via Giorgio la Pira and Via Gino Capponi.  The garden retains its original layout but now the collection includes tropical plants as well as flora native to Tuscany.  Close to this garden complex there are some specialized museums like the Museum of Mineralogy (a geology collection includes fossils; the mineralogy section shows the geological structure of Elba, whose ores attracted bronze traders in the 10th century BC) and the Botanical Museum (the most important in Italy).