THE PLANT GROUPS 119 



(3) Drawings. Construct an outline figure (no cells) 

 of the cross section of the stem of Pteris. Label 

 the parts accurately. Discuss briefly the distinc- 

 tive features of the anatomy of the eagle fern as 

 compared with that of Adiantum. 

 o. Minute anatomy. 



(1) Transverse sections. Work out and draw the cellu- 



lar structure of one vascular strand of the rhizome 

 in Pteris and label accurately. Draw also a few 

 cells of the epidermal, of the skeletal, and of the 

 storage tissues. 



(2) Long sections. 



(a) /Skeletal tissue. Work out and draw a few cells 

 of the strengthening, or skeletal, tissue as 

 seen in long section. Are these cells living ? 

 What are their most distinctive structural 

 characteristics? Explain in your notes. 



(5) Vascular tissues. Study the vascular tissues 

 in long section. Find the sieve tubes of the 

 phloem and water-conducting cells, or 

 tracheids, of the xylem. Determine the 

 shape, size, and wall markings of each type 



of cell element. 



(c) Sieve tubes. Find in the sections the abundant 



sieve plates. Consult text figures. Be able 

 to discuss the structure and function of the 

 sieve plates. Draw accurately one or more 

 sieve tubes and the adjoining cells. 



(d) Tracheids. Study the form, cell contents, and 



cell-wall thickening of the tracheids. How 

 does the tracheid differ from the duct, or 

 vessel, of the higher plants ? Is it as efficient 

 in water conduction as the vessels are? 



