All plant geography must begin with the discovery of a plant in the field and rests on the correct identification and naming of this plant and the accurate recording of the place of discovery. Without the collection of specimens and the recording of localities in the field, there could be no subject ‘plant geography’. If the geographical coordinates are accurately recorded, along with further details about the locality at which the specimen was collected, the herbarium specimen provides unambiguous and enduring evidence of that plant’s occurrence at the given site. A fully labelled and well curated herbarium specimen safeguards the basic data of the plant geographer but it does not, in itself, safeguard the scientific naming of the plant so preserved. This is the job of the International Code of Botanical Nomenclature, which governs the scientific naming of all plants except cultivars, the naming of which is governed by a separate code.