The Xanthophyceae belong to the groups of algae that have received somewhat less attention in studies over the past few decades. Compared to other algae, the increase in newly described species is lower. This is also reflected in the few reports about their distribution and ecology. Exceptions are only those forms that are immediately recognizable, morphologically striking, and therefore more frequently listed among the species. Since the freshwater flora primarily serves as a reference work, it has been kept somewhat more conservative in this regard. I have omitted some new biochemical and ultrastructural concepts of systematics because too little evidence has been gathered so far. Further investigations may show that some Xanthophyceae are green algae that, under certain circumstances, do not store starch and whose chromatophores are more...