212 ROTANY OF THE LIVING PLANT 



of the parent, as in the Potato ; or it may be the result of rupture 

 or death of the tissue connecting it with the parent, as in the bulbils 

 of the Orange Lily. It is the separation that defines the new indivi- 

 dual. In origin it was a part of the parent plant, the characters of 

 which it retains and repeats. The process may be simply described as 

 budding ; or more specifically as somatic budding, as it involves the 

 detachment of some part of the soma, or plant-body. 



The other method is by sexual reproduction, which involves the 

 fusion of two sexual cells, or gametes, to form a new cell, the Zygote. 

 This is also the starting point of a new individual. The two gametes 

 are more or less distinct from one another in origin and character. 

 The offspring shows features derived from both of the parent gametes. 

 But it differs in some degree from either of them. The process is 

 not then a mere act of repetition, as the budding is. On the contrary, 

 Sexual Reproduction may be a source of something different from either 

 parent, though it shares the qualities of both. 



Vegetative propagation is a very wide-spread means of increase 

 both of wild plants and of those in cultivation, and there is considerable 

 variety of detail in the way in which it is carried out. In Flowering 

 Plants it consists in the independent establishment of buds. Such 

 buds may be produced in the normal sequence, as axillary buds ; or 

 they may be produced out of the normal sequence, as adventitious 

 buds. Examples of each will first be taken from plants growing 

 naturally, and later it will be seen how the art of the cultivator makes 

 use of these, or actually induces their production artificially. 



The propagation by buds formed in the normal sequence sometimes 

 involves no modification of the shoot, and is so simple a process that 

 it is hardly distinguished from ordinary normal growth. An example 

 is seen in the Canadian Water- Weed (Elodea). The shoot produces 

 axillary buds which grow into long branches. Either mechanical 

 rupture, or progressive decay from below, may sever the physiological 

 connection, and the branch becomes a new individual. Elodea shows 

 also the indefinite degree to which this vegetative propagation may 

 extend ; for since the plant was introduced about the middle of the 

 nineteenth century, it has spread throughout the water-ways of Britain, 

 notwithstanding that only the female plant was introduced ; and, being 

 dioecious, it does not propagate here by seed. This simplest of all 

 methods of vegetative increase in numbers is very common. Ordinary 

 perennials, such as Grasses and Sedges, give abundant examples 

 of it. 



Jn other plants some slight modification of the axillary buds may 



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