Impossible to press? – Succulents in Renaissance herbaria

Several Renaissance herbaria, including the herbarium by Caspar Bauhin, contain preserved specimens of different succulent plants, such as cacti, stonecrops, palm lilies or aloes. In view of the difficulties experienced even today when preparing succulents for the herbarium, the efforts of the Renaissance botanists to meet this challenge is remarkable. The view that succulents by definition are unsuitable for pressing for the herbarium, as for instance expressed by Richard Bradley in his 1716 book, prevails to these days. We first provide a condensed overview of standard preparation techniques for succulents advocated in the literature of the past forty years. Then, a selection of specimens of succulents in early herbaria, from several plant families, is discussed and the preparation methods used at that time, and possible solutions of the difficulties involved, are outlined.