70 LABORATORY PRACTICE CHAP, xm 



2. The close contact between this extension and the wood 



of the host. 



3. The suckers or projections from the extension into the 



wood of the host. (These are found only in the 

 European Mistletoe ( Viscum album). 



4. Make a sketch to show these points. 



V. The Mistletoe, then, not only grows upon another 

 plant, but it sends its roots (viz. the " extensions ") down into 

 the substance of that plant to draw away its sap instead of 

 hanging them out into the air as the Orchid does. The 

 Mistletoe is a parasite, living at the expense of another plant. 



It is also a green parasite, and takes only crude sap (i.e. 

 the sap passing up from the roots to the leaves) from its 

 host, but it still possesses green leaves like other plants to 

 take materials from the air and to work over or elaborate 

 the materials obtained in these two ways for its own benefit. 



VI. Take a piece of the Dodder together with a portion 

 of the host plant around which it is entwined. Notice : 



3. The slender twining stem destitute of leaves. 



2. The direction in which it twines about the stem of the 



host plant. (Compare Chapter XII, I and II.) 



3. The absence of a root at the lower end. (For the pur- 



pose of demonstrating this point, it will be necessary 

 to examine young plants where they grow.) 



4. The small suckers, arising from the stem and penetrat- 



ing the host plant. 



5. The color of the stem and suckers. 



6. The flowers, if any are present. 



7. Make a sketch to show these points. 



8. Are the suckers root-, stem-, or leaf-structures? 



9. Why does the Dodder lack leaves of any appreciable 



size? 



