CHAPTER VI 



STRUCTURE OF THE STEM 



STEM OP 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 intemodes. 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 4;he 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 asjibro- 

 vascular bundles (Fig. 52). 



Split a portion of the stem 

 lengthwise into thin translucent CT.fibro-Tascular bundles ; ^c, pithy material 



,. , .. 1. .1 it, between bundles, 



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. — Dia^ammatic Cross-Section 

 of Stem of Indian Com." 



