The Morphology of Protonema and Bud Formation in the Bryales

Abstract

The development of protonema from spore in aseptic culture was followed in species representing 14 genera and 7 orders of the Bryales. In no case could a distinction be made between sharply defined ‘chloronema’ and ‘caulonema’ stages. In all species, with the exception of the anomalous Cinclidotus fontinaloides, the protonema developed a markedly heterotrichous habit, with prostrate filaments of relatively unlimited growth and erect filaments of more restricted development. The two types of filament were usually distinct in cellular characteristics as well as in the direction of growth. In some cultures a third type of filament grew downwards into the medium. Shoot buds were found to occupy diverse positions in different species, but the commonest position was near the base of a primary filament of the erect branch system. Shoot buds were formed as readily in artificial light of sufficient intensity as in natural daylight.