His best known popular work is his "Dictionary of Plant Names", which found its way into the libraries of most horticulturalists. One of the focuses of his work at the Natural History Museum was the flora of the Caribbean, where he carried out field work. Stearn continued to return to the Cambridge Botanic Garden, cared for his own garden and worked with the RHS to become an authority on horticulture as well as botany. William Stearn collaborated with his wife, Eldwyth Ruth Stearn, on a number of his most important works, including "Botanical Latin" and "Dictionary of Plant Names" and translating German botanical history into English. Just before his death he completed a revision of his original "Epimedium" monograph.