A MANUAL OF BOTANY • 11 



Observe, further, how soon the roots form branches. In 

 the bean, for example, what effect would the formation of 

 root branches have on the elongating hypocotyl ? 



Does the pea act in the same manner or not ? 



In the corn, oats, and some other seeds, observe that some 

 roots arise from other parts of the young plant than the 

 radicle end of the hypocotyl. These are secondary or 

 adventitious roots. 



Draw the various forms of roots mentioned above, not 

 omitting the seed name in your drawings. 



Root hairs. Position. Examine young radish, oat, or corn 

 roots of vigorous growth and observe the fine hairs (^root 

 hairs) covering a portion of the surface. With reference 

 to the root tips where are these hairs? What is their 

 form ? What is their size and color ? Use* (771)^ and (Ip) and 

 study carefully. Offer any explanation you can for their 

 absence from the root tip. To understand this, take a 

 well-grown corn or pea seedling, rule black ink marks at 

 equal distances from the seed to root tip and replace in the 

 growing position. Examine twenty-four and forty-eight 

 hours later and observe the relative position of the marks. 

 Where does the root have its linear growth, or growth in 

 length? What effect on the root hairs would growth in 

 their immediate vicinity have? Examine the varying 

 colors of the corn root and see if any correspondence exists 

 between color and place of growth. 



Make drawings showing results of your observations on 

 root hairs and place of growth. 



Structure of root tip. Examine (Ip) the root tips of 

 radish, oats, or onion seedlings. Observe the shape and 

 minute structure of the extreme end (root caj)). What is 

 the purpose of this part of the root ? 



Examine the root in the region of the root hairs and 



1 Throupjhout the Manual (m) signifies use the hand lens; (Ip) the 

 low and (hp) the high power of the compound microscope. 



