Dr J. J. Smith is best known by his studies about Orchidaceae. But since 1904 he published regularly in collaboration with Dr J. C. Costerus in the ”Annales du Jardin Botanique de Buitenzorg“, the results of their researches in teratology of tropical plants. Some years ago, Dr J. J. Smith was so kind to ask me if I would like to continue their studies in tropical teratology; I accepted this invitation. Although botanists appreciate this part of the botanical science in more than one way, and although even the opinion about the definition of a monstrosity differs, it must be stated that what has been done by Costerus and Smith in this field of the botanical science, deserves our high appreciation as they have described and pictured for the first time a large number of tropical monstrosities.