The family Acoraceae comprises only one genus, Acorus, with two widespread species: A. calamus in Eurasia and North America and A. gramineus in East and Southeast Asia. The general part covers 10 pages and includes paragraphs on distribution, ecology, pollination (here reported for the first time), dispersal, morphology, fruits and seeds, seedling morphology, pollen morphology, vegetative anatomy, flower anatomy, seed anatomy, cytology, phytochemistry, fossils, uses, relationships and conservation. The family, genus and species are described and annotated; there is also a key to the species.