Uncommon Karyological Features in the Anther Tapetum of some Pedicularieae (Scrophulariaceae)

Abstract

SUMMARYThe karyological events in the anther tapetum during the premeiotic and meiotic period of development have been studied in Pedicularis, Barista, Odontites, Euphrasia, Bel-lardia, Melampyrum, Tozzia, and Lathraea. The one-layered inner tapetum becomes bi- or plurinucleate already prior to the onset of meiosis, with the exception of Pedicularis where it remains uninucleate diploid during this period. The outer tapetum always persists in the uninucleate diploid level until meiosis starts. Chromosome augmentation during the meiotic period follows two different ways: in Pedicularis and Melampyrum disturbed mitoses and formation of restitution nuclei are characteristic, in the remaining genera endomitoses (exact sense) regularly occur. In Barista and Lathraea restricted to the outer tapetum additionally to the endomitoses always undisturbed acytokinetic mitoses during the early meiotic period take place. Therefore in the Pedicularieae there exist two different types of the cellur plurinucleate tapetum: a...