MOSSES, LIVERWORTS, AND FERNS 281 



GROUP B. BRYOPHYTES 



CLASS I. HEPATIC^: (liverworts). Genus used as illustration 



Marchantia 

 CLASS II. Mirsci (mosses). Leading genera used as illustrations 



Atrichum and Sphagnum 

 GROUP C. PTKRIDOPHYTES 



CLASS I. FiLicm,*: (the true ferns). Leading genera used as illus- 

 trations Pteris (the bracken fern), Adianlum (the maidenhair 



fern), Onoclea (the sensitive fern, or oak fern) 

 CLASS II. EQUISETIN*: (horsetails, or scouring rushes). Genus used 



as illustration Equisetum (the only living genus of the class) 

 CLASS III. LYCOPODIN*: (club mosses or ground pines). Genus used 



as illustration Lycopodium (one of the three living genera of 



the class) 



PROBLEMS 



1. Of what importance are mosses as soil formers? 



2. What is the significance of the radial arrangement of the leaves 

 of the moss plants ? 



3. Why is it important to the plants that the asexual spores of 

 mosses, liverworts, and ferns should have wide distribution ? 



4. In what sense is it true that the vascular tissue exemplified in 

 ferns means about the same to the plant kingdom as the vertebral 

 column (backbone) means to the animal kingdom? 



5. Why is it that peat-bog moss is good material for covering the soil 

 of potted plants and for packing fragile articles for shipping? 



6. In what ways may ferns be propagated vegetatively? How do 

 florists propagate their ferns? 



7. What structures of ferns help to explain the fact that most ferns 

 thrive best in damp and shaded regions? 



8. In museums that you have visited what fossil evidences are there 

 that ferns lived during former ages? 



