A letter of 1652 by the Italian scientist Cassiano dal Pozzo sheds new light on the Roman activity of the Dutch still-life painter Otto Marseus van Schrieck. Dal Pozzo writes to the Florentine botanist Giovanni Nardi to say that he intends having 'Otho Merceus' make drawings of a precious specimen of a 'cedrato', a type of citrus fruit, which he has received from the Medici garden. That drawing on vellum will enable him to make this discovery known to his friends. The Dutch master is said to have worked for him on at least one other occasion with satisfactory results. This commission by Dal Pozzo places Otto Marseus van Schrieck as a botanical draughtsman at the centre of a group of early modern scientists, the members of the Accademia del Linceo. They included the Florentine cardinals Leopoldo and Gian Carlo de' Medici, both of whom are also known as Italian patrons of the artist. Early sources, among them Balthasar Monconys's diary, already state that Van Schrieck made many drawings for his own use while in Italy, presumably botanical ones, among others. It was not known that he also did so professionally at the time. Later in life, back in Holland, he made comparable botanical studies on commission for Agneta Block.