The RHS Lindley Library, London
Libraries are an exceptionally valuable fund of learning and knowledge and scattered across the globe are a number which have accumulated special collections of horticultural and botanical works.

In addition to books, these libraries also hold collections of Nursery Catalogues which, though often dismissed as ephemera, are the first place of publication of the great majority of cultivar names making them essential to the study of cultivated plant taxonomy. 

An extensive list of American libraries which incorporate significant collections of horticultural works can be found on the website of the Council on Botanical and Horticultural Libraries.