214 



A TEXTBOOK OF BOTANY 



[Ch. V, 1 



soil on the bark. Sometime^;, when exposed to the light, 

 young roots will turn red, apparently through formation of 

 erythrophyll, whieh may have any of the meanings already 

 explained for that substance (page 88). 



In duration, roots conform to the plants which produce 

 them, being annual, biennial, or perennial, and either herba- 

 ceous or woody. 



9M 







*^^^^ 



Unlike shoots, 

 however, roots 

 drop no parts, 

 for the growing 

 tips develop 

 -without break 

 into the older 

 and thicker, 

 and finally the 

 woody parts. 



Roots are pro- 

 duced from 

 stems, most 

 commonly and 

 typically from 

 the lower end of 

 the first stem 

 formed by the 

 embrj'o plant ; 

 but sometimes 

 they develop 

 from other parts, particularly from the nodes where these 

 happen to touch the ground. Further, many kinds of 

 plants, like the common "Geraniums," which do not 

 naturally produce roots from their stems, can be made to 

 do so from slips or cuttings, though this is impossible with 

 most kinds. Sometimes, though rarely, roots produce stems, 

 as in Locusts and Apple trees, which send up suckers from 

 their roots at a distance from the trunks. 



Fig. 157. 



■ A typical tap root, of Dandelion. 

 (From Bailey.) 



