CHAPTER VI 



STRUCTURE OF THE STEM 



STEM OF MONOCOTYLEDONOUS PLANTS 



96, Gross Structure. Refer back to the sketches of the corn- 

 seedling, to recall something of the early history of the corn-stem. 

 Study the external appearance of a piece of corn-stem or bamboo 

 two feet or more in length. Note the character of the outer surface. 

 Sketch the whole piece and label the enlarged nodes and the nearly 

 cylindrical internodes. Cut across a corn-stem and examine the cut sur- 

 face with the magnifying glass. 

 Make some sections as thin as 

 they can be cut and examine 

 with the magnifying glass 

 (holding them up to the light) 

 or with a dissecting microscope. 

 Note the firm rind, composed 

 of the epidermis and underlying 

 tissue, the large mass of pith 

 composing the main bulk of the 

 stem, and the many little harder 

 and more opaque spots, which 

 are the cut-off ends of the 

 woody threads known asj6ro- 

 vascular bundles (Fig. 52). 



Split a portion of the stern 

 lengthwise into thin translucent ci>, fibro-vascular bundles ; gc, pithy material 

 slices and notice whether the 



bundles seem to run straight up and down its length ; sketch the 

 entire section x 2. Every fibro-vascular bundle of the stem passes out- 

 ward through some node in order to connect with some fibro-vascular 



83 



FIG. 52. Diagrammatic Cross-Section 

 of Stem of Indian Corn. 



