96 THE BOOK OF NATURE STUDY 



and when the multiplication in number of individuals is thus 

 carried on by the vegetative organs we speak of vegetative or 

 asexual reproduction. The special organ of reproduction of the 

 flowering plants is, however, the flower, from which, as a result 

 of complicated processes, into which we shall not enter in detail, 

 the seeds are formed and separated as the reproductive bodies 

 from which new plants arise. Since two minute parts or cells 

 of the plant have to unite to give rise to the new individual in 

 the seed, the reproduction effected by the flower is distinguished 

 as sexual reproduction. Both vegetative and sexual reproduction 

 are found in the Creeping Buttercup (Ranunculus rep ens). 



This plant spreads vegetatively by means of the creeping 

 branches already mentioned as arising in the axils of some of the 

 lower leaves. These branches, which are called runners, have 



elongated inter- 

 nodes, and do not 

 stand erect but lie 

 along the surface 

 of the soil. At 

 each node is a 

 single foliage-leaf, 



FIG. 51. Runner of Creeping Buttercup. (After Baillon.) m tne axl1 of which 



is a bud. This 



bud grows rapidly, and sends down a number of roots into 

 the soil; it thus comes to possess all the vegetative organs 

 of a complete plant. At first the new plants that are 

 established in this way all around the parent are connected 

 to the latter by the runners, but in time the internodes of 

 these decay and the new plants become independent. It is 

 most instructive to select a strong plant of the Creeping Butter- 

 cup growing in open ground, and to trace the spread of new 

 plants around it. Many of the runners are a yard or more in 

 length, and may give rise to a number of plants. Probably most 

 of the plants of this kind of Buttercup that are met with have 

 arisen vegetatively. It is much more difficult to be sure that 

 a plant of Ranunculus repens has come from a seed than it is in 

 the case of either of the other two common species which have 

 no runners. In considering the success and the means of 



