This is a monographic herbarium collection relating to Araceae Lemnoideae, a group of aquatic plants known as ‘duckweed’, of which Elias Landolt (1926-2013), of Zurich, was perhaps the world’s leading expert. The collection is directly linked to the living collection housed at the Institute of Agricultural Biology and Biotechnology in Milan (CNR-IBBA-MI; see
https://registry.gbif.org/collection/24fdf8b9-2165-44a5-9e30-019a2190331d)x. It was donated to Florence in 2026 by Landolt’s heirs, thanks to the intervention of the National Research Council (CNR).