Guidelines for the effective and ethical sampling of herbaria.

The use of herbaria for science and conservation is enabling greatly enhanced scopes and scales of discovery, exploration and protection of biodiversity. The availability of digital, open-access herbarium data is, perhaps counter-intuitively, expanding the use of physical collections by researchers who use digital collections to find specimens and then sample physical collections for multiomics investigations, including genomics, transcriptomics, metabolomics, proteomics and microbiomics. These investigations are leading to new scientific insights and supporting the development of conservation actions, but they come with a substantial cost: the partial or complete destruction of often irreplaceable specimens, which constitute a global heritage that should be permanently safeguarded for future reference. Here we provide a set of recommended best practices for the sustainable, equitable and ethical sampling of herbarium specimens. Our recommendations are intended for two complementary and partially overlapping audiences-users and stewards-who together build, use and protect herbarium collections.