198 I The Process of Evolution 



ground among the leaves, never open and are self-pollinated within 

 the bud. Seeds from these flowers, virtually sown at dehiscence, 

 produce plants genetically similar to the parents. Thus three modes 

 of reproduction, providing different amounts of genetic recombina- 

 tion, occur in the same plant at the same time. 



Somewhat more cryptic sorts of vegetative reproduction, without 

 the formation of seeds, also are known. These include some instances 

 of so-called "vivipary" in plants. That is, the propagules are tiny 

 bulbils which occur in the inflorescences and may replace the 

 flowers. Some species of Allium (onion. Fig. 9.8), for example, as 

 well as some Poa (bluegrass) species reproduce in this fashion. 

 From a developmental point of view, one may say that the indi- 



Fig. 9.8 I Onion {Allium) showing some flowers 

 in inflorescence replaced by bulbils. 



