De platte vorm van Lemna gibba, nog steeds een probleem

A flat Lemna, obviously different from L. minor L., has been referred to as the flat form of L. gibba L. by DE LANGE & SEGAL (1968). L. gibba is able to produce flat fronds but this alone is insufficient evidence for the conclusion that the flat Lemna, so common in our waters, is only a pessimum form of it and not a separate taxon. From the literature it appears that the typical L. gibba includes at least 3 distinguishable races which show differences in the flowering process. The complete generative cycle of the flat Lemna has been observed in Belgium and in California. It comprises at least 2 races with respect to the flowering biology. According to the existing literature data it is proterogynic; in Leiden an unisexual male plant has been found.