The application of plant names is inextricably linked to type specimens, and understandably considerable resources and effort have been spent over the past several years on creating and disseminating images of such specimens, for example through JSTOR Global Plants (JGP). As part of a gap analysis of images of types accessible on the worldwide web, 512 names, including 276 that are names of accepted taxa, published in the genus Agave and types with which they are associated were investigated to determine the state of our knowledge of the nomenclature of this horticulturally popular and economically important genus. The electronically available type specimens of the 192 names of Agave established by William Trelease, the most prolific author of plant names in the genus, are analysed in some detail and ten of his names are typified. In addition, the accuracy of the information associated with web-accessible type specimens of Agave names is recorded. We established that 76% of the images of Agave name types are associated with incorrect metadata.