STUDIES OF SPORE-PLANTS 245 



spores which germinate to produce a new moss plant. 

 Obviously, the moss plant corresponds to the fern prothal- 

 lium, because each is produced from a spore and each is a 

 gametophyte and produces sex-organs. Moreover, the moss 

 sporogonium and the fern plant both develop from fertilized 

 egg-cells, and produce asexual spores. This relation is ex- 

 pressed in diagram form as follows, the dashes indicating the 

 order of stages. 



Fern spore pro thallium (gametophyte) sex-cells fern plant 

 (sporophyte) spores. 



Moss spore moss plant (gametophyte) sex cells sporo- 

 gonium (sporophyte) spores. 



The striking difference is that the spore-forming stage 

 (sporophyte) is the short-lived and relatively inconspicuous 

 sporogonium of the moss and the prominent fern plant. On 

 the other hand, the sex-generation (gametophyte) of the fern 

 is the prothallium which few people ever see, and in the moss 

 it is the well-known plant. 



234. Allies of Mosses : Bryophytes. The only close 

 relatives of mosses are the liverworts, of which Marchantia is 

 an example common in greenhouses. The mosses and liver- 

 worts together constitute a group known as Bryophytes (mean- 

 ing moss-plants). Certain lichens ( 248) and other plants 

 are sometimes mistaken for true mosses. See relation of 

 mosses to other groups of plants in table of classification in 

 133. 



H. LOWER SPORE PLANTS* 



235. Algae and Fungi. So far all plants studied (seed- 

 plants, ferns, mosses) have more or less similarity. Even 

 mosses have the working equivalent of the roots, stem, and 

 leaves as seen in the higher seed-plants. We shall next study 

 some types of still lower and simpler plants, which in fact 



* The higher spore-plants are the ferns and mosses, described in the fore- 

 going sections. 



