1)2 



PRINCIPLES OF PLANT-TERATOLOGY. 



number of carpels as compared with that of members 

 of the other whorls of the flower, it is quite common 

 to find what we may regard with 

 almost complete certainty as a 

 reversion to a larger number, 

 sometimes to that typical of the 

 other whorls. 



A flower of the toad flax (Linaria 

 vulgar is) had five carpels instead of 

 the two characteristic of the order 

 Scrophulariaceae ; in this case the 

 original number five, of which all 

 whorls of the flower once were 

 composed, has been restored. 



In the Leguminosae there has 

 been very great reduction in the 

 gynoeceum, which has been left 

 with only a single carpel. Rever- 

 sions, partial or complete, would 

 be expected to occur from time 

 to time. Mimosa has occasionally 

 produced five carpels : a case of 

 complete reversion to the number 

 of members possessed by the other 

 whorls. Flowers of Trifoliam 

 repens were seen with two and 

 three carpels respectively (fig. 

 101), and those of the scarlet 

 runner (Phaseolus mu/tiflorus) 

 with two (fig. 102) ; in this last 

 case the extra carpel is not alwaj^s 

 so well developed as the others, 

 sometimes being almost vestigial ; 

 as Drabble and others describe, 

 the two carpels, which are placed 

 in the antero-posterior plane, are 

 sometimes fused by their ventral 

 sutures so as to form a bilocular ovary, at other 

 times by their margins to form a unilocular ovary. 



Fig. 102. — Phaseolus midti- 

 flon.is (Scarlet Runner) 

 Bicarpellary fruit form- 

 ing a syncarpous ovary, 

 with section. 



