33 cactus paintings from the library of Salm-Reifferscheid-Dyck are reproduced in colour as a set for the first time^*, along with a tabulation of probable dates and modern names. Evidence points to Salm-Dyck himself as the artist of most of them, and to around 1805 as the date, when he was a pupil of Redouté. A few later additions are mainly by other hands. Salm-Dyck wrote most of the captions, as is shown from a study of his manuscript notebooks, which are collated here for the first time. Apart from their obvious artistic merit, the paintings are valuable as early illustrations of cacti (columnar cerei mostly) in cultivation in Europe, and as potential lectotypes for Salm-Dyck's names.