THE PLANT GROUPS 123 



2. Life history. 



a. Construct a graphical life history of the fern similar to 



that of Ricciocarpus. 



b. Contrast briefly in your notes the alternating genera- 



tions of the fern and the bryophyte. 



B. EQUISETALES (HORSETAILS) 

 SPOROPHYTE 



Compare the main subdivisions of the plant body of some 

 species of Equisetum with that of the true ferns as regards 

 both form and function. 



1. The plant body and its plan. 



a. Main subdivisions. Has the Equisetum plant the same 



divisions into horizontal rhizome, aerial green leaves, 

 and roots as the true ferns ? What organs perform the 

 functions of photosynthesis, absorption, conduction, 

 and storage ? What portions would carry the plant 

 over winter or extreme drouth ? How does Equisetum 

 differ from ferns as regards the above points ? 



b. Vegetative parts. Is the main stem segmented into 



regular nodes and iuternodes ? Is the leaf-and- 

 brauch arrangement cyclic or spiral ? Determine 

 the origin of lateral buds and branches with refer- 

 ence to the leaves. Is it the same as in higher 

 plants ? Compare the aerial and underground stem 

 and lateral branches in these respects. Are they 

 all constructed on the same plan ? Note any varia- 

 tions that may occur. Observe the origin and nature 

 of the roots. 



c. Strolili, or reproductive cones. Observe these structures 



and their position on the plant. Are their parts 

 (as seen externally) arranged on the same plan as 



