In all these cases, however, the end-cells of the filaments each give rise to a carpospore, and the aggregate of such sporiferous filaments is a cystocarp. Again, in the family of the Gelidiaceae, the single filament arising from the carpogonium grows back into the tissue and preys upon the cells of the axis and larger branches, after which the end-cells give rise to carpospores and a diffused cystocarp is formed.
When the cystocarp is produced externally, it may form a berry-like mass without an envelope, in which case it is known as a favella.
Polysiphonia sp., section through young cystocarp.
If the sporophyte generation is confined to the cystocarp, is the tetrasporiferous plant, as has been suggested, merely a potential gametophyte reproducing by a process analogous to the budformation of the Bryophyta?
Phillips, " The Development of the Cystocarp in Rhodymeniales," i.