STEMS, BULBS AND BUDS 57 



LABORATORY EXERCISES. 



Exercise 1. Dicotyledonous Htem. Examine thin cross-sections of stems 

 of Begonia or Geranium. Note the epidermis, fibro-vascular bundles and 

 ground system or pith. Note the number of layers of epidermal cells; the 

 cuticularized outer cell walls of the outer layer of cells; the trichomes; 

 the arrangement of the fibro-vascular bundles; the phloem and xylem 

 parts of the bundles. Determine so far as possible all the tissues that 

 can be recognized in the cross-section of the stem. Give special attention to 

 the fibro-vascular bundle. 



Exercise 2. Examine cross-sections of one-, two- and three-year-old stems 

 of basswood and note the number of fibro-vascular bundles, medullary 

 rays, pith and formation of external covering. 



Exercise 3. Examine thin sections of bark or older woody stems and note 

 the cork cells. 



Exercise -^. Monocotyledonous Stem. Study the arrangement and 

 structure of the fibro-vascular bundles in cross and longitudinal sections 

 of stems of corn. Locate the tissues so far as possible. 



Exercise •>. Study the arrangement of the bundles in cross-sections of a 

 grass or grain plant. 



Exercise 6. Examine tlie stems of several trees. Note the arrangemen,t 

 of the buds and lea* scars. Also note the lentlcels. 



Exercise 7. Examine a cross-section cut through the lenticel and note 

 the character of the cells. 



Exercise S. Examine several types of bulbs, including onion, hyacinth, 

 tulip, crocus, and such other plants as may be available. Note the short 

 stem or axis and the scales. 



Exercise 9. Examine two or more types of underground stems, including 

 the tuber of the potato. Note the nodes, internodes, buds and lenticels. 



Exercise 10. Examine the end of a large woody stem and note annular 

 rings, medullary rays and pith. 



Exercise 11. Select a large bud from a tree and split lengthwise. Com- 

 pare with a bulb. . ., 



Exercise 12. Select a large bud and dissect carefully, comparing the 

 outer scales and inner leaves. 



