Claes Fredrik Hornstedt, Swedish medical doctor and naturalist, studied botany at Uppsala under Carl P. Thunberg*, completing a dissertation on the plants Thunberg had collected in South Africa and Asia. During his student days he undertook a journey to Lapland to collect plants and animals. On Thunberg's recommendation he undertook a collecting tour to the East Indies during 1782-1785, bringing back plants, animals, minerals and ethnological material. On his way to the East he arrived in False Bay on 26 May 1783 for a stay of two weeks. He found the Cape Flats very dry and the plants faded, but none the less collected many specimens. On the return journey he again stayed at the Cape, from 22 October to 22 December 1784. He climbed Table Mountain on 12 December and collected plants, insects and birds, particularly at the Stellenburg and Weltevreden estates (near Plumstead), which belonged to a Swede, Mr Cachman. Upon his return to Sweden he presented his collections to King Gustaf III. They were later transferred to the Riksmuseum, Stockholm.
Hornstedt compiled a paper, "Descriptiones animalium praestantiorum; confectae in itinere orientali, in primis per Javam, Sumatram et Caput Bonae Spei" in 1784, but it was never published. The manuscript is in the archives of Svenska Literatur Sällskapet in Helsinki, Finland. His voyage to the East was described in "Anteckningar under en resa till Ostindien aren 1782-86" (Notes on a voyage to the East Indies 1782-86), edited by Ernst Lagus and published in Svenska Literatur Sällskapet i Finland (1888, Vol. 10). After his return he studied at the University of Greifswald, Germany (then under Sweden), and qualified as Doctor of Medicine in 1786 with a thesis of 31 pages on the edible fruits of Java. Returning to Sweden he became a lecturer in natural history at Linköping. During 1787-1788 he was acting curator of the Naturalienkabinett of the Swedish Academy of Sciences (the precursor of the Riksmuseum), while its curator, A. Sparrman*, was in West Africa. In 1796 he entered the Swedish navy and was stationed at Fort Svaeborg in the Gulf of Finland. When the fortress was taken over by Russia in 1808 he changed to their service, but died the next year. The East Indian plant genus Hornstedtia was named in his honour.