134 LABORATORY AND FIELD EXERCISES 



respects is the process in cycads intermediate between 

 that in ferns and that in the mandrake. 



5. Structure of the seed. Study the structures of the seed 



in Zamia from specimens or from figures. Compare its 

 structure with that of the mandrake and the pea. What 

 sporophytic and gametophytic structures are comprised 

 in the seed of Zamia ? If specimens are available, draw 

 a sectional view of the cycad seed to show the parts of 

 the embryo and the remaining structures of the seed. 



6. Seed germination. The method of seed germination in 



cycads is well illustrated by the germination of the 

 acorns, or seeds, of the oak. The important things to 

 note are 



a. The structure of the seed and embyro. 



b. The exit of the embyro from the hard seed coat. 



c. The function of the cotyledons and the exit of the 



plumule. 



d. The final adjustment of the young plantlet in the 



soil and air. 



If the acorn is used, make appropriate drawings to 

 illustrate stages a-d. 



7. Life history. Study the text diagrams in the graphical 



life history of Zamia. Be able to label and explain 

 each stage of the life history illustrated in the diagram. 



8. Summary. Summarize briefly the following points relat- 



ing to the structure and reproduction of Zamia and 

 the Cycadales. 



a. Summarize the fernlike characteristics of Cycadales 



which indicate their pteridophyte ancestry. 



b. Summarize their new gymnosperm characters. 



c. Give briefly the characteristics in which Cycadales are 



intermediate between PteridopJiyta and the higher 

 seed plants. 



