EQUISETUM ARVENSE. 119 



3. The location of the chlorophyll-bearing cells. 



4. The stomata and their location. (Compare with sur- 

 face view.) 



5. The location of vascular bundles. 



6. Draw. 



II. THE SPOROPHYLLS. 



Remove a few of the sporophylls, and lay in water so that 

 they may be seen from different directions. Observe: 



1. The form of the outer parts of the sporophylls. 



2. The central stalk. 



3. The number and position of the sporangia. 



4. Draw. 



Tear open some of the sporangia, mount and observe under 

 the microscope: 



5. The spores, whose outer wall forms: 



6. The elaters. Note the position of the elaters when the 

 spores are moist. Allow some spores to dry on a slide 

 while watching them, and note the position and behavior 

 of the elaters as they become dry. 



7. Draw. 



ANNOTATIONS. 



Equisetum arvense shows at least two features not yet 

 seen in any of the plants studied, although one of these 

 exists in some of the true ferns. First, the spore-bearing 

 shoot is separated from the green vegetative shoot; and 

 secondly, the sporophylls upon this spore-bearing shoot 

 are distinctly unlike foliage leaves, as we commonly 

 know them, and are gathered into a compact cone-like 

 cluster. All the chlorophyll work is done by the branched 

 shoots, the leaves doing none and apparently serving 



