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TEXTBOOK OF BOTANY 



The parts of Marchantia and Porella just described are the game- 

 tophyte phases of these two Hverworts. They bear archegonia and 

 antheridia in which eggs and sperms are formed much as in the mosses. 

 The sporophyte phase develops from the fertihzed egg and is similar to 

 the sporophvtes of certain mosses (Figs. 303 and 304). 



Fig. 304. Antheridial and archegonial thalli of Pallavicinia (A-B); stages in the 

 development of the sporophyte (C-I). Courtesy of World Book Co. 



Reduction division occurs when the spores are formed in the spo- 

 rangium. When a spore germinates, a new thallus develops from it. 

 Elongated, spindle-shaped, and often spirally thickened cells known as 

 elaters may develop within the sporangia along with the spores. This is 

 one of the characteristics of liverworts. 



Some of the features by which mosses can be distinguished from 

 liverworts may be summarized as follows: 



Mosses Liverworts 



Stems leafy, never thalloid Stems leafy or thalloid 



Protonema present No protonema 



Many-celled branching rhizoids One-celled rhizoids 



Elaters absent from sporangia Elaters present in sporangia 



REFERENCES 



Dixon, H. N. Student's Handbook of British Mosses. 3rd ed. Wheldon and 



Wesley, London. 1924. 

 Frye, T. C, and Lois Clark. Hepaticae of North America. Univ. of Washing,- 



ton Publications in Biology. 6:1-161. 1937. 



