The sporogonium of the liverworts is in the simpler forms simply a spore-capstile with arrangements for the development, protection and distribution of the spores.
Morphological identity) between the differentiated tissues of an Anthocerotean sporogonium and those of the sporophyte in the higher plants.
In the stalk of the sporogonium there is a similar strand, which is of course not in direct connection with, but continues the conduction of water from, the strand of the gametophytic axis.
The central hydrom strand in the seta of the sporogonium of most mosses has already been alluded to.
Thus the histological differentiation of the sporogonium of the higher mosses is one of considerable complexity; but there is here even less reason to suppose that these tissues have any homology (phylogenetic community of origin) with the similar ones met with in the higher plants.
The structure of the stomata of the sporophyte of vascular plants is fundamentally the same as that of the stomata on the sporogonium of the true mosses and of the liverwort A nihoceros.
There is here obviously a certain parallelism with the case of Bryophyta, where the sporogonium arising from the oospore is epiphytic and partially parasitic upon the female plant, and always culminates in the production of spores.
It may be regarded as derived from a wholly dependent sporogonium not unlike that of some of the simpler Bryophyta; the latter are assumed to have arisen from primitive Algal forms, in which, as the first step in the interpolation of the second generation in the life cycle, the fertilized ovum gave rise to a group of swarm spores, each of which developed into a new sexual plant.
Not even Riccia, with its rudimentary sporogonium, has so simple a corresponding stage as Bangia, for, while there is some amount of sterile tissue in Riccia, in Bangia the oospore completely divides to form carpospores.