THE PLANT GROUPS 127 



2. Asexual reproduction. 



a. Observe the strobili of a lycopod which is bearing spores. 



What is the position of the strobilus on the stem? 

 Are its parts of the same general nature and arrange- 

 ment as those of the main axis? 



b. Structure of strobilus, sporangia, and spores. Determine 



these points by dissecting the leaves, or sporophylls, 

 from strobili. How is the sporangium related to the 

 scalelike leaves (sporophylls) which bear them ? How 

 and where do the sporangia open (dehisce) to shed 

 the spores ? Are the spores numerous and all of one 

 kind, namely, homosporous ? 



c. Draw a single sporophyll with its sporangium. 



3. Analysis. Analyze two or more species of lycopods and 



record your analyses as for ferns and equiseta. 



4. Distinctive characters. Summarize the characters which 



seem to you to distinguish lycopods from other Pteri- 

 dophyta studied. 



SELAGINELLA 

 SPOROPHYTE 



Study one or more species of Selaginella with reference 

 to the following more important and distinctive features of 

 these plants: 



1. Body plan and adjustment of organs to the environment. 

 a. Leaves. 



(1) Note their arrangement and adjustment to light. 



If erect and creeping species are available, com- 

 pare them in these respects. 



(2) Note the ligule, a small outgrowth on the adaxial side 



near the stem. This is an ancestral character which 

 existed in the lycopods of early geologic periods. 



