Juvenile gametophyte development in the Blasiales. 3. Sporeling ontogeny of Cavicularia densa

Sporeling development in Cavicularia densa was determined using controlled culture and light microscopy techniques. Ontogeny is typified by endosporic germination followed by early protonematal development via the production of a terminal quadrant of four cells which ruptures the spore wall distally. Sporeling production is triggered by the delimitation of a cuneate apical cell in one of the quadrants. Regular apical cell segmentation produces derivatives and adult merophytes that ultimately result in a juvenile Cavicularia gametophyte. The fundamental sporeling pattern exhibited by Cavicularia is shared only with that of its sister genus Blasia. Moreover, the patterns of sporeling and gemma/gemmaling ontogeny in Cavicularia and Blasia share quadrant systems of precise uniformity, thus reinforcing the close relationship between the blasialean genera.