The identities of three plants of unknown origin revealed by ancient paintings

Archives and correspondences are often overlooked resources in assessing taxonomic and nomenclatural information and this sometimes affects taxonomic proposals. Here we show that unpublished illustrations not only can definitively help in identifying unresolved or poorly known names but can be themselves original material and sometimes must serve as types, avoiding neotypes or misleading synonymizations. We present the case of three names introduced by the Neapolitan botanist Michele Tenore (Muscari strangwaysii, Asparagaceae; Pogostemon suavis and Salvia menthifolia, Lamiaceae). They have been interpreted differently over time because herbarium specimens that constituted original material were not accurately searched for (M. strangwaysii) or were unavailable (P. suavis, S. menthifolia). Although these three names are currently synonymized (with M. neglectum, P. cablin, and S. chamaedryoides) we demonstrate that these synonymies are not correct, based on the detailed study of original nineteenth-century watercolour paintings, a re-examination of protologues and specimens preserved in the Botanical Garden of Naples (NAP). The watercolour paintings are crucial for application of the names, because diagnostic features often disappear with drying (M. strangwaysii), or because they are the only extant original material (P. suavis). In all three cases we introduce new typifications for the names and update the synonymy to M. botryoides, P. heyneanus, and S. microphylla, respectively.