A flower of Spirodela polyrhiza of the clone used in the experiments arises in the left reproductive pocket of a frond at the proximal part of the meristematic area outside the part which gives rise to daughter fronds. If the medium is unfavourable for vegetative multiplication of fronds, flowers can be produced by not completely exhausted older fronds and their still attached daughter fronds. Sometimes the flowers or inflorescences produce 1 to 5 roots.