The Herbarium of the Natural History and Science Museum of the University of Porto (MHNC-UP) (registered in the Index Herbariorum as PO Herbarium) is an active collection in continuous growth that contains about 100,000 herbarium specimens of fungi, lichens, algae, bryophytes, pteridophytes and vascular plants. The history of botany at Porto University is inseparable from the origins of the first specimens of bryophytes and lichens collected by Isaac Newton in 1848, in mainland Portugal. The majority of specimens of PO Herbarium were collected in Portugal, but this collection also includes a General Herbarium with specimens from countries worldwide obtained through a versatile exchange policy during the last three centuries.