A VENA SATIVA. 173 



1. The roots. 



2. The upright main axis, the stem, with numerous 

 branches near the top. 



3. The lateral appendages of the stem, the leaves. 



4. The surface appendages on the roots and leaves, the 

 trichomes, in both instances extremely minute. 



B. THE ROOTS. In a plant which has the emptied 

 grain from which it grew still attached, note 



1. The small group of roots arising from one end of the 

 grain, the strongest of which is fat primary root. 



2. The stem emerging from the other end, the first inter - 

 node of the stem. 



3. At a certain point, 1 the second node of the stem, a whorl 

 of secondary roots. 



4. At one or two succeeding nodes, a like whorl of sec- 

 ondary roots. 



5. Make a diagram, showing the position of the roots 

 and their relation to the lower part of the stem. 



Cut a transverse section of one of the large secondary 

 roots. Examine by transmitted light. Note 



6. The round central spot of firmer tissue, \.\\z fibro-vas- 

 en Jar bundle. The openings in it are the larger vessels. 



7. The loose, pith-like cortical portion. 



8. The root-hairs, attached to the edge. 



9. Draw. 



1 Known to agriculturists as the " tillering point." The length of 

 this first internode depends to a considerable extent on the depth of plant- 

 ing the seed. 



