228 



BOTANY 



In artificial reproduction detached pieces of plants are made use of for the 

 purpose of producing a fresh complete plant. In many cases this is easily done, 

 but in others it is more difficult, or even impossible. The favourite and easiest 

 method is by means of cuttings, that is, the planting of cut branches in water, sand, 

 or earth, in which they take root (Pelargonia, Tradescantias, Fuchsias, Willows, etc.). 

 Many plants may be propagated from even a single leaf or portion of a leaf, as, for 

 instance, is usually the case with Begonias. The young plants spring from the end 

 of the leaf-stalk, or from its point of union with the leaf-blade, or from the ribs, 

 particularly when they are artificially broken or incised. In other cases the leaves, 

 while still on the parent plant, have the power to produce adventitious buds, and, 



Flo. 193.— Different modes of grafting 



I, Crown grafting ; II, splice grafting ; III, bud grafting ; 

 If, stock ; E, scion. 



in this way, give rise to new plants (see Vegetative Reproduction, p. 279). Even 

 from roots or pieces of roots it is also possible to propagate some few plants. An 

 example of this is afforded by Ipecacuanha, whose roots are cut in pieces and then 

 sown like seeds. The Dandelion possesses the same capability of developing from 

 small portions of the root, and to this peculiarity is due the difficulty with which 

 it is destroyed. 



In grafting or budding, cuttings from one plant are inserted in another, so that 

 they grow together to form physiologically one plant. The union is accomplished 

 by means of a callus (p. 144), formed by both the scion and the adopted stock. 

 Vessels and sieve-tubes afterwards develop in the callus, and so join together the 

 similarly functioning elements of both parts. Such an organic union is only 

 possible between very nearly related plants, thus, for example, of the Amygdalaceae, 

 the Plum, Peach, Almond, Apricot, may readily he grafted one upon the other, or 

 of the Pomaceae, the Apple with the Quince ; but not the Apple with the Plum. 



