LIVERWORTS 



4°3 



Note that although a sporogonium is a sporophyte, 

 these two words are not synonymous. A sporogonium is a 

 particular kind of structure which occurs only in bryo- 

 phytes. Sporophyte has a much broader meaning. It 

 names the generation which produces spores whatever its 

 form may be. It may be a sporogonium, as in bryophytes, 

 or a large plant, as in seed plants. You remember that 

 seed plants produce pollen, and that a grain of pollen is a 

 spore. Therefore the generation which produces pollen 

 must be a sporophyte. 



C. Leafy Liverworts. — There is a group of liverworts 

 whose bodies are divided into distinct stems and leaves 

 which look much like moss stems and leaves. These liver- 

 worts are often mistaken for mosses, but they are different 

 from mosses in that they have distinct upper and under 

 surfaces. They are often found on moist and shaded bark. 

 Such liverworts are called leafy ox f otiose in distinction from 

 those, like Marchantia, which are thallose. 



D. Green Sporogonia. — There is a kind of thallose liver- 

 wort which produces a sporogonium which contains chloro- 

 phyll. This sporogonium grows up from a prostrate 

 thallus and looks a good deal like a blade of grass. (See 

 Figure IQ9.) This liverwort is Anthoceros. It is not very 

 common. Its archegonia are not borne on erect arche- 

 goniophores as in Marchantia, but are found embedded in 

 the thallus. 



This green sporogonium of Anthoceros is important be- 

 cause it forecasts what we find in the ferns, namely, the 

 two generations growing as independent plants, each manu- 

 facturing its own food. Although the sporogonium of 



