His most important work was Contributions to the Botany of South America (1870); other well-known works were On the Apocynaceae of South America (1878) and Illustrations of South American Plants (1789-1879).
主著は3巻の"Contributions to the Botany of South America"(1870)で、他に "On the Apocynaceae of South America" (1878)や"Illustrations of South American Plants" (1789-1879)などがある。