108 LABORATORY AND FIELD EXERCISES 



observed ? Draw the sporophyte or the sporophyte and 

 surrounding tissues if studied in section. Label the 

 parts according to function. 



b. Dissemination of spores. Are there any distinct devices 



for spore dissemination in the sporophyte that you 

 are studying ? How would the spores be liberated ? 

 What is the nature of the spore cell and how is it 

 adapted for dissemination and for withstanding dessi- 

 cation, or drying, by wind and sun ? 



c. Comparisons. Is the sporophyte a new structure in 



plants studied thus far ? What is its particular use, 

 or function, in the life history of the amphibious 

 liverworts ? Would such a structure be equally use- 

 ful in the life history of the fresh-water algse ? 

 2. Life history. Write a graphical life history of the liver- 

 wort that you are studying, similar to the life histories 

 already written for Spirogyra and fungi. Explain in 

 your notes the special adaptations of the gametophyte 

 and the sporophyte to seasonal conditions and changes. 



B. MUSCI (MOSSES) 

 GAMETOPHYTE 



1. Habitat. What is the usual habitat of mosses ? Are they 

 for the most part mesophytes, hydrophytes, or xero- 

 phytes in habitat and structure ? Do you know of 

 exceptions to the general rule ? Can you think of ad- 

 vantages to be derived from the clustered habit of 

 growth of the mosses ? Would this habit be of any 

 advantage in securing food, moisture, and light, or in 

 insuring fertilization of eggs by the motile sperms of 

 mosses ? Summarize your ideas of habitat in your 

 notes. 



