THE ANGIOSPERMAE 



1213 



two " solid " carpels, which form the replum and are extended centripetally 

 to form the false septum. The lateral portions of the ovary, those which are 

 detached at maturity, are said to be two sterile valve carpels, the whole 

 structure being thus quadricarpellary, not bicarpellary, as usually under- 

 stood. The pseudo-valve type is said to be typical of most Papilionaceae 

 and in combination with valve carpels it occurs in some Berberidaceae, and 

 in combination with solid carpels in Orchidaceae. 



A brief statement of the theory cannot do justice to the considerable 

 array of detailed evidence which Saunders has presented in support of it, in 

 spite of which the theory has been adversely criticized, and has obtained 

 little credence. This is not the place to attempt to weigh up the merits of 

 the controversy, but we should point out that the analysis of the compound 

 ovary, on any carpellary basis, is theoretical and any theory, even the 

 classical theory, despite its respectable antiquity, can only be maintained so 

 long as it is not inconsistent with observation (Fig. 1181). 



Fig. 1 181. —Various theories of carpel structure. Transverse and longitudinal sections. 

 A, Formal sections. B, Viin Tieghem. C, Saunders. D. Hagerup. E, Thomas. F. 

 Thompson-Gregoire. (After Ozerida.) 



Axis. 



Fertile carpels. 



md 



Sterile 

 carpels 

 or Bracts 



Polymorphy of carpels, in a factual sense, may be seen in certain genera 

 and is better described as heterocarpy. It is, however, rare, except in the 

 Compositae, where there is frequently a difference between the carpels, or 

 rather the fruits, of the ray florets and those of the disc florets. Though 

 usually slight, the difference is very marked in Dimorphotheca (Fig. 1182), 

 while in Calendula, although only the ray florets produce fruits, there are 

 three different forms among them. In some species of Atriplex and Cheno- 



