38 ESSEXTIALS OF BOTANY 



the secondary roots arise. If possible, peel off the cortical portion 

 from one stained root and leave the central cylinder with the sec- 

 ondary roots attached. Stain one section with iodine and sketch it. 

 Where is the starch of this root mainly stored ? 



Test some bits of parsnip for proteids by boiling them for a 

 minute or two with strong nitric acid. 



A^'hat kind of plant-food does the taste of cooked parsnips show 

 them to contain? [On no account taste the bits which have been 

 boiled in the poisonous nitric acid.] 



48. Storage in Other Roots. ^- The parsnip is by no 

 means a remarkable plant in its capacity for root^storage. 

 The roots of the yam and the sweet potato contain a good 

 deal of sugar and much more starch than is found in the 

 parsnip. Beet-roots contain so much sugar that a large part 

 of the sugar supply of Europe and an increasing portion 

 of our own supply is obtained from them. Oftentimes the 

 bulk of a fleshy root is exceedingly large as compared with 

 that of the parts of the plant above ground. 



A good example of this occurs in a plant,^ related to the 

 morning-glory and the sweet potato, found in the south- 

 eastern United States, which has a root of forty or fifty 

 pounds weight. 



Not infrequently roots have a bitter or nauseous taste, 

 as in the case of the chicory, the dandelion, and the 

 rhubarb, and a good many, like the monkshood, the yellow 

 jasmine, and the pinkroot, are poisonous. Can you give 

 any reason why the plant may be benefited by the dis- 

 gusting taste or poisonous nature of its roots? 



49. Use of the Food stored in Fleshy Roots. — The 

 parsnip, beet, carrot, and turnip are biennial plants; that 

 is, they do not produce seed until the second summer or 

 fall after they are planted. 



1 Ipomma Jalapa. 



