A taxonomic monograph of the Eurasian holoparasitic plant genus Lathraea L. (Orobanchaceae)

A taxonomic monograph is presented for Lathraea L. (Orobanchaceae), a genus of holoparasitic plants distributed across Europe and Asia. Plants in this genus are characterised by their underground stems, achlorophyllous scales with internal gland-lined cavities, and, in some species, explosive seed dehiscence. Despite their conspicuousness, no taxonomic treatment of the genus has been written since 1930. Our work draws upon extensive international field data and a comprehensive survey of herbarium specimens. Detailed descriptions are provided for each species, along with full synonymy, distribution maps, and notes on habitat, host specificity, phenology, ecology, ethnobotany and threat risk. We present evidence to consolidate Lathraea into five species, resolving taxonomic confusion. The infrageneric classification is reviewed and a key to species is provided. Species are illustrated with photographs of living and dried material.