60 BOTANY FOR BEGINNERS CHAP, v 



radicles. Those roots which are formed from the primary roots are 

 called secondary roots. When roots grow out of the secondary roots 

 they are known as tertiary roots. 



Other kinds of Roots. Adventitious roots are produced from stems, 

 leaves, and roots without any regular order. Clinging roots are adven- 

 titious roots used to fix a plant to a support. Aerial roots hang down 

 in the air and take water from it, or enable a plant to climb. Water 

 roots are produced by water-plants, and do not produce root-hairs. 

 Parasitic roots penetrate into a host-plant and extract nourishment from 

 it. Modified roots have undergone a change, so as to serve as a store- 

 house of reserve material. 



Shapes of Roots. May be conical, napiform, fusiform, tubercular, 

 fibrous. 



Uses of Roots. (a] They anchor the plant to the soil, (b) They 

 obtain nourishment from the soil, (c) Food may be stored up in them. 

 (d) They may be used for climbing, &c. 



Movements of Roots. Roots are always moving from place to place, 

 so as to find food and the line of least resistance. 



QUESTIONS ON CHAPTER V. 



(1) Describe and explain, with reference to examples, the peculiarities 

 of the roots of biennial plants. (1890. ) 



(2) What is a growing point? How does the growing point of a root 

 differ from that of the stem ? ( 1 889. ) 



(3) Briefly describe, giving examples, the principal kinds of roots ; 

 and explain what are the functions which the various kinds of roots are 

 specially adapted to perform. 



(4) How do roots parcel out the soil ? Give examples. 



(5) Give sketches showing (a) conical, (b} napiform, (c) fusiform 

 roots. 



(6) What is an adventitious root ? Mention plants which produce 

 such roots, and give an account of their function. 



(7) What is a parasite ? How do the seeds of the Mistletoe find their 

 way to the host plant ? How does the seed act when it germinates ? 



(8) What is a root parasite ? Give examples. 



(9) Of what use is a root ? In what circumstances may a plant 

 exist without one ? 



(10) Explain why the root of a turnip first grows faster than the stem, 

 and then stops while the stem grows. 



(n) Give an account of experiments which you have performed to 

 show how roots move. 



(12) In preparing sketches you have to show the scale. What is 

 meant by the scale, and how can it be determined ? 



