42 



P. R. WYCHERLEY 



The plants showing this proliferation may be divided into two classes. Firstly, those 

 whose spikelets are usually proliferated ; secondly, those in which proliferation is an 

 ephemeral character. 



In the first class the proliferated condition appears season after season, even when 

 plants are transplanted from their natural habitats; their offspring, moreover, inherit the 

 characteristic. In this group the cause is primarily genetic, and environmental factors 

 are apparently secondary. The plants of this type form the ' viviparous races,' propagating 

 themselves by plantlets formed from the deciduous leafy upper part of the proliferated 

 spikelets. 



2. Terminology 



Before discussing the viviparous races and, later, the problem of proliferation as a 

 whole, it is necessary to review the terminology used in relation to this phenomenon. 



The detached leafy buds are often described as bulbils, but Poa hulbosa L. var. 

 vivipara Koel. is the only grass in which they are truly " bulbous." Bulbifery is not 

 a satisfactory term, since it is applied to plants which bear bulbils in parts other than 

 the inflorescence, e.g. Dentaria bulbifera L. 



Fig. 2. Festuca ovina L. Carmarthen Fan, 14.ix.l950. Seed of an upper floret germinating in situ. Note 



the coleoptile (x c.7). 



' Chloranthie ' is found in the French literature and in German ' auswachsende 

 Ahrchen,' 'Laubsprossen' and 'Vergriinung' are used. However, in literature in Dutch, 

 English, French, and German may be found words derived from the Latin ' viviparus ' 

 and ' prolifer.* Unfortunately there is confusion in their use. 



The derivatives of ' viviparus ' were introduced by Linnaeus (1737). It is not clear 

 from his description if this was because of a superficial likeness to an undetached seed 

 germinating, or if he actually thought this to be the case. The term does indicate the 

 ecologically significant fact that the propagules are dispersed in a ' living ' (i.e. not dor- 

 mant) condition in most cases. Nannfeldt (1940) restricts the use of the term ' vivipary * 

 to those races in which the deciduous buds form the regular diaspores. 



' Vivipary ' is restricted by Pope (1949) to embryos developing continuously without 

 any dormant period. He induced this in barley by supplying water directly to exposed 

 germs. Such uninterrupted growth occurs in maize with defective endosperms (Eyster 



