4 ROOT AND SHOOT [CH. 



simple characteristics. For instance the Mistletoe sends 

 its roots into the tissues of poplars and other trees, 

 and most of the roots of the Ivy are affixed to the bark 

 of a tree, or to the wall up which it climbs : in these cases 

 it would be absurd to define the root-system as that 

 part of the plant which descends into the soil ; and, not 

 to multiply examples, such considerations have forced 

 botanists to be somewhat more precise in other points 

 of the definition. 



Without going further than is justified by the aims 

 of a work like the present, it may suffice to point out 

 that all the plants we have to deal with agree in the 

 following particulars. 



True roots never bear leaves or flowers or fruits ; 

 whereas the most characteristic features of the shoot- 

 system are furnished by these particular appendages. 

 And even in cases, not exemplified by any of the trees 

 or shrubs here to be considered, where roots branch on 

 the aerial parts of other plants and even turn green and 

 flatten out, and in other ways behave unlike the ordinary 

 roots of ordinary plants, they do not habitually produce 

 branches of unlike nature, bearing green leaves, buds, 

 tendrils, flowers and fruits, as does the shoot-system. 



In the case of any ordinary shrub or tree, therefore, 

 all that we are in the habit of seeing above the ground 

 is the shoot-system, the root-system being underground, 

 and, apart from difficult cases to be specially examined 

 and discussed, the difference is sufficiently marked by 

 this: we can, however, include the various classes of shoot- 

 system still more completely by adding to the definition 

 that the shoot-system bears the leaves, the flowers and 

 the reproductive organs proper. 



In the case of our more familiar plants it is obvious 

 that we may add yet other characters to aid in defining 



