The Sorghum Ontology is part of the Crop Ontology (CO) project. The Crop Ontology has been created to compile validated concepts along with their inter-relationships on anatomy, structure and phenotype of Crops, on trait measurement and methods as well as on Germplasm with the multi-crop passport terms. The concepts of the CO are being used to curate agronomic databases and describe the data. The use of ontology terms to describe agronomic phenotypes and the accurate mapping of these descriptions into databases is important in comparative phenotypic and genotypic studies across species and gene-discovery experiments as it provides harmonized description of the data and therefore facilitates the retrieval of information.