32 ELEMENTS OF BOTANY. 



sections from the split surface and examine with the high power, with 

 and without staining with iodine. 



Notice the appearance of the wood-cells and the ducts as seen in these 

 sections, and compare with Tig. 41. i 



45. Structure of Fleshy Boots. — In some fleshy roots, such 

 as the beet, the nature and relation of the parts is rather 

 puzzling, since they form many layers of tissue in a single 

 season, showing on the cross-section of the root a series of 

 layers which look a little like the annual rings of trees, as 

 shown in Fig. 40. 



The structure of the turnip, radish, carrot, and parsnip is 

 simpler. 



Cut a parsnip across a little below the middle, and stand the cut end 

 in red ink for 24 hours. 



Then examine by slicing off successive portions from the upper end. 

 Sketch some of the sections thus made. In what portion of the root did 

 the colored liquid rise most readily ? Cut thin cross-sections of the ink- 

 stained parsnip at several points along its length, and examine first with 

 the low, then with a moderately high power of the microscope. The 

 ring of red ink marks the boundary between bark and wood. Is the 

 main bulk of the parsnip bark or wood ? Is this ring marked by the 

 presence of any particular kind of cell ? Examine a longitudinal section 

 to help you to answer the question. Cut thin transverse sections from 

 an ink-stained parsnip and notice how the medullary rays run out into 

 the bark. Stain one such section (from the slender- portion of the root) 

 with iodine, and sketch it as seen under a low power of the microscope. 

 Where is the starch of this root mainly stored ? 



46. Use of the Nourishment stored, in Fleshy Boots. — The 

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

 they produce seed during the second summer or fall after 

 they are planted. 



The first season's work consists mainly in producing the 

 nourishment which is stored in the roots. To such storage is 

 due their characteristic fleshy appearance. If this root is 



1 The examination of the minute structure of the root is purposely made very 

 hasty, since the detailed study of the structural elements can be made to better 

 advantage in the stem. 



