Structure and Development of Symphyogyna brasiliensis

Abstract

1. The thallus of Symphyogyna brasiliensis grows by means of a cuneate apical cell. Branching is generally apical but sometimes ventral and adventitious. 2. The thalli are strictly dioecious, the male plants being smaller than the female. 3. The antheridia are crowded and scattered irregularly in a long band lying above the midrib, each inclosed by a posterior involucre. 4. Development of the antheridium follows the general pattern of the anacrogynous Jungermanniales. 5. The archegonia are in isolated dorsal groups of about twelve, each group on a pad and covered by a posterior involucre. 6. In the development of the archegonium, generally six neck canal cells are formed before the ventral canal cell and egg are differentiated. 7. The number of neck canal cells is later increased, often up to twelve or fifteen; since some of these are binucleate, there are often as many as twenty neck canal nuclei. 8. The venter becomes 2-layered before fertilization. 9. The embryogeny follows the sequence of stages previously described for other species.