Catalogue of the rare plants growing at Eltham, London, in the collection of James Sherard, who, after making a fortune as an apothecary, devoted himself to gardening and music. For this work Dillenius wrote the text and executed 324 plates. The book was described by Linnaeus, who spent a month with him at Oxford in 1736, and afterwards dedicated his Critica Botanica to him, as opus botanicum quo absolutius mundus non vidit, "a botanical work of which the world has not seen one more authoritative."   

"According to Blanche Henrey^[10] it [Hortus Elthamensis] was "the most important book to be published in England during the eighteenth century on the plants growing in a private garden" and a major work for the pre-Linnaean taxonomy of South African plants, notably the succulents of the Cape Province. Dillenius' herbarium specimens from Eltham are preserved in the herbarium of the Oxford Botanical Garden." (Wikipedia article on James Sherard, accessed 2-2020).

Digital facsimile from Real Jardín Botánico at this link.