In the botanical world, naming is key to classification. Naming is hugely complex and the rules and practices around it have become increasingly codified. Naming a new plant involves not just the proper form of a name, but also a designated object that is an example of the name.
In 1930 botanists finally came up with a unified universal system for new names for plants. Aside from the requirements of the format of the name and that it be in latin the International Code of Botanical Nomenclature has some requirements about specimen backing up the name. “Since 1990 it has been necessary to identify the exact specimen that is to be the nomenclatural type of the taxon and the herbarium in which the specimen is located.” In other words, every name has a specific plant specimen that it refers to. The specimen is part of the name so to speak. Any questions about the name are resolved by reference to the specimen. Around the world there are a few key herbariums that hold these specimen. The NYBG, Kew Gardens and Musee National d’Histoire Naturelle are the big ones.
There are even specific names to designate how a specimen came into a herbarium. A holotype is a specimen that was specified by the person creating the plant name. If a plant name was created (say 50 years ago) and no specimen was designated at the time, a later botanist can designate a specimen for the name (taxon), in which case the specimen is a lectotype. If the holotype or lectotype is destroyed and a new specimen is found to replace it that is called a neotype.