English: Duckweeds belong to the order Alismatales and the Araceae family, an early branch-off from the monocotyledonous crown ancestor. In agreement with previous classifications70, (a) shows a phylogenetic tree of plastid-rbcL (ribulose-1, 5-bisphosphate carboxylase large-subunit) genes of two dicots—Arabidopsis thaliana (Brassicales, NC_000932.1) and tomato (Solanales, NC_007898.2); three monocots Spirodela polyrhiza (Alismatales, NC_015891.1), rice (Poales, NC_001320.1) and banana (Zingiberales, EU017045.1), and water-lily as an outgroup (Nuphar advena, Nymphaeales, NC_008788). (b) shows a ventral view of Spirodela, illustrating schematically the clonal, vegetative propagation of duckweeds (redrawn and simplified from Landolt). Daughter fronds (F1) originate from the vegetative node (No), from the mother frond F0 and remain attached to it by the stipule (Sti), which eventually breaks off, thereby releasing a new plant cluster. Daughter fronds may already initiate new fronds (F2) themselves before full maturity. Roots are attached at the prophyllum (P). (c) illustrates the progressive reduction from a leaf-like body with several veins and unbranched roots to a thallus-like morphology in the Lemnoideae, redrawn after historical illustrations ‘Das Pflanzenreich’ from www.biolib.de; Sp: Spirodela polyrhiza, Le: Lemna minor, Wo: Wolffia arrhiza.