190 Plant Biology 



Porella is similar to that of Maichantia, consisting of a foot, stalk, and 

 sporangium (capsule). The latter bears spores and elaters as in the 

 thalloid liverworts. 



QUESTIONS AND TOPICS 



1. List the characteristics of (1) Embryophyta, (2) Bryophyta, (3) Hepaticae, 

 and (4) Musci. 



2. Learn the pronunciation, derivation, and a definition of each new term used 

 in this chapter. 



3. Discuss the economic importance of bryophytes. 



4. Contrast gametophytes and sporophytes in as many ways as possible as illus- 

 trated by the bryophytes. 



5. Make a diagram of a true moss life cycle showing the stages in correct 

 sequence and the chromosome numbers in the gametophyte and sporophyte 

 generations. 



6. Make a diagram of a liverwort life cycle showing the stages in correct 

 sequence and the chromosome numbers in the gametophyte and sporophyte 

 generations. 



7. Why are the axes, "leaves," and rhizoids not considered to be true stems, 

 leaves, and roots? 



8. Why are the mosses and their alhes classed as Embryophytes ? 



9. Why are the bryophytes considered not to have true vascular (conducting) 

 tissues? 



10. In what ways do the leafy liverworts resemble certain mosses? 



IL In what ways do the leafy liverworts differ from the thalloid liverworts? 



12. How do the gametangia of Bryophyta differ from the gametangia of Thal- 

 lophyta? 



13. Why do the bryophytes require a considerable amount of moisture? 



14. List some of the more important values of Sphagnum mosses. 



15. Explain why most bryophytes are rather short plants, giving specific reasons 

 because of structures, growing conditions, etc. 



16. Describe the structure and functions of elaters. 



17. Describe differences in structures of the zygote developments in the mosses 

 and in the liverworts. (Contrast protonema and prothallus. ) 



18. Describe the method of determination of sex in bryophytes. In what ways 

 are these methods similar to the sex determination methods in man? 



SELECTED REFERENCES 



Conard: How to Know the Mosses, William C. Brown Co. 

 Evans: Classification of the Hepaticae, Botanical Review 5: 49-96, 1939. 

 Grout: Mosses With a Hand Lens, A. J. Grout, Newfane, Vt. 

 Grout: Mosses With a Hand Lens and Microscope, A. J. Grout, Newfane, Vt. 

 Smith: Cryptogamic Botany (vol. 2): Bryophytes and Pteridophytes, McGraw- 

 Hill Book Co., Inc. 

 Verdoorn et al.: Manual of Bryology, Chronica Botanica Co. 



