6 



ELEMENTS OF BOTANY. 



dowed many plants with the power of puttuig forth roots as occasion may 

 require from an}^ part of the stem, or even, in some instances, from the 

 leaves, thus giving them a double hold on life : such are denominated 

 secondary or adventitious roots. The common strawberry of our 

 gardens will serve as an illustration of one kind of adventitious roots. 

 This plant produces " runners," which put forth roots at the point where 

 they touch ground, then a cluster of leaves, and a new plant is formed. 

 The stems of the I'unning blackberry (Bubus Canadensis L.) often root freely 

 also, and form a netting for the feet of the unwary. Very many illustra- 

 tions of plants endowed with this power might be found anywhere about 



Fig. 12. — Common ivy (Hedera ffelix), with adventitious roots. 



US, but it remains for the skilful gardener to develop it to its fullest ex- 

 tent, as his cuttings of roses, geraniums, and indeed of almost all his rarest 

 and most beautiful blooming plants abundantly testify. 



Such adventitious roots are, however, true roots, which perform the 

 ordinary functions of such organs. There are other adventitious roots of 

 an entirely different character. The stem of the poison ivy (Bhiis Toxicoden- 

 dron L.), when growing beside some object to which it can cling, puts, 

 forth roots in innumerable numbers which do not contribute in any de- 

 gree whatever to the nourishment of the plant, but merely afford mechan- 

 ical support. Moreover, these roots appear to be produced in response to 



