CHAPTER V 



ROOTS 



63. General character. — The root i.s a tlilnl promiiiont 

 plant organ, and it presents even a greater variety of i-ela- 

 tions than leaf or stem. In whatever relation it is fonnd 

 it is either an aljsorlx-nt organ or a holdfast, and very often 

 both. For sneh work no light-relation is necessary, as in 

 the case of foliage leaves ; and there is no leaf-relation, as 

 in the case of stems. Eoots related to the soil maj' be 

 taken as an illustration. 



It is evident that a soil root anchors the plant in the 

 soil, and also absorbs water from the soil. If absdrption is 

 considered, it is farther evident that tlie amount of it will 

 depend in some measure ujion the amount of surface which 

 the roots expose to the soil. We have alreadv noticed that 

 the foliage leaf has tlie same prolilem of exjiosure. and it 

 solves it bv Ijccoming an exjianded organ. Tlje (pu'stion 

 mav be fairlv asked, therefore, "whv are Udt roots expanded 

 organs? The reeei\'ing of rays of light, and the al)Sorbing 

 of water ai'c verv dilfei'ent in their demands. In the former 

 case a flat surfa.ce is demanded, in tlie latter tulnilar pro- 

 cesses. The increase of surface iu tlie root, therefore, is 

 obtained not by exiianding the organ, luit Ijv multiplying 

 it. Besides, to obtain the soil water the roots must barrow 

 in every direction, and must send out tlieir delicate thread- 

 like l.iranches to cmne in contact with as much soil as pos- 

 sible. Fartherniore. in soil roots absorjition is not the only 

 thing to consider, for the roots act as holdfasts and must 

 cjrapple the soil. This is certainly done far more effectively 



