ABSTRACT:
The first comprehensive monograph of Lemnaceae, the duckweeds, was written by Christof Friedrich Hegelmaier in 1868. The Lemnaceae were considered by most authors as closely related to the Araceae. Engler (1876) himself included the duckweeds as a subfamily, Lemnoideae, with two tribes in the Araceae, but later as a separate family (Engler, 1889).