A SEM study of the oospore wall ornamentation in Polish charophytes (Charales, Charophyceae) - genera Lychnothamnus, Nitella and Nitellopsis

The taxonomic importance of oospore characters has long been recognized. Many authors believed such oospore characters to be constant and characteristic for each species and associated with the morphological characters that are useful taxonomically. The ornamentation can be helpful in taxonomy, if oospore ornamentation characters are conservative in nature, which is more common in the genus Nitella than in Chara. In the present investigation scanning electron microscopy (SEM) was used to study the oospore wall ornamentations of all species from the three genera: Lychnothamnus, and Nitellopsis that can be found in Poland. Based on new findings and other investigations of the oospore wall ornamentation, taxonomic problems concerning many of the investigated species are discussed.