A class of the * Chlorophyta containing one order, the Oedogoniales, comprising three genera of filamentous algae. These algae are characterized by an unusual kind of cell division, which results in parallel rings of closely spaced 'caps' of old cell wall material being formed at the anterior end of dividing cells. Prior to cell division a ring of wall material forms at the anterior end of the cell. Nuclear division then occurs and the two resulting nuclei become separated by a septum, which, however, is not contiguous with the outer wall at this stage. Meanwhile the ring of wall material at the top of the cell enlarges and the old cell wall to the outside of the ring ruptures. The new wall material is then free to extend and forms the outer walls of the new cell. Part of the old wall remains as a 'cap' at the upper end of this cell. The septum between the daughter nuclei moves up to fuse with the base of the new wall material and cell division is completed (see diagram). The zoospores of the Oedogoniophyceae are also peculiar in having numerous flagella forming an apical ring.  |
