This Instruction document describes the procedure to report plant species present in the ICOS stations to the ETC. The species classification (to be done in the field or in the lab) is not discussed here because it is a standard procedure that must be done by experts in the station team. The reference nomenclature has to follow the approach of The Plant List database (http://www.theplantlist.org), where multiple taxonomic data sources were merged taking into consideration internationally accepted names and synonymy relationships, and adding additional names and synonymy relationships from regional and national floristic datasets. Further details on the database are available on the original website. The Plant List is a work in progress and, therefore, it may undergo updates; for this reason the website is the reference to be used.