38 ESSENTIALS 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. 
What 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 Ipomea Jalapa. 
