GAMETOPHYTE 203 



green leaves. In the plants which have a stalk and capsule, (1) 

 the stalk grows out of the leafy plant. 



Sporophyte. The capsule is the sporangium (2). The stalk 

 and capsule together form the sporophyte (spo'ro-fit) or spore- 

 producing generation of the moss. 



Gametophyte. The spore (3) germinates into a threadlike pro- 

 tonema. The protonema soon develops rhizoids (4), and tiny 

 buds appear which form the adult plants. These may grow only 

 leaves, or they may develop into plants (5) that bear the rosettes 

 of leaves which hold either sperm or egg cells, for these are pro- 

 duced on separate plants. These two kinds of plants form the 

 sexual generation (called the gametophyte) of the moss (6, 7, 8, 

 9). After a sperm has been transferred to the egg cell, fertiliza- 

 tion or fusion of these two cells takes place (10). This process 

 results in the growth of the sporophyte which bears the asexual 

 spores. These spores produce a leafy moss plant which bears 

 organs producing eggs and sperms. This life history is known as 

 alternation of generations. 



Practical Exercise 6. Why do we call the life history of moss alternation of 

 generations ? 



BRYOPHYTA 



HepaticaeV \_M^c^ci 



liver ^^t^fF mo$-$- 



These plants are small and live mostly on land. There are about 16,000 known species. 



Self-Testing Exercise 



Bryophytes include (1) and (2). The mosses 



show (3) of generations in which an (4) stage is 



followed by a (5) stage. A spore gives rise to a (6) 



