THE INFLORESCENCE. AND THE FLOWER 



269 



it may be referred to a fading out of the activity of the floral shoot, 

 or even a deficiency of room for the full number of parts. The result 

 is that the carpels are frequently fewer than the other parts. For 

 instance, in the Compositae, the Umbelliferae, and most Gamopetals 

 there are only two carpels in the pentamerous flower. But in many 

 cases it is clear that the smaller number is the result of abortion of 

 parts which comparison with allied plants would show as actually 

 present. Sometimes those parts are represented by vestigial remains, 



Fig. 193. 



Flower of Veronica Chamaedrys, typically pentamerous, but the posterior sepal 

 is abortive : the two obliquely posterior petals are fully fused to form apparently 

 one : only the two obliquely posterior stamens are developed. 



marking the position which those parts should hold, though they do 

 not come to functional maturity. A good case of a vestigial stamen 

 (st.) is seen in Scrophularia (Fig. 192). 



Meiomery may appear in any of the floral parts ; often it is seen in several of 

 them in the same flower. A complete whorl may be absent : for instance the 

 corolla in the Pearl-Wort (Sagina apetala) in the Pink Family, and Glaux among 

 the Primroses : or one of the whorls of stamens may be absent, as in the Prim- 

 rose. The most marked examples in the androecium are related to increasing 

 precision of the floral mechanism. For instance in the Orchidaceae, derived 

 from an Amaryllidaceous type with six stamens, Anastasia has three, 

 Cypripedium two, and Orchis only one— the anterior stamen. Ginger has also 

 only one, but it is the posterior. All of these are highly specialised types : 

 their meiomery by abortion has followed parallel, but quite distinct lines. The 

 Valerianaceae show various degrees of abortion of the stamens ; but they also 



