THE CARPEL 233 



together by ventral union with a central receptacle. Inclusion of Nigella 

 and Butotniis among examples of false coenocarpy is based on misin- 

 terpretation of the "core" of the gynoecium, which is called the re- 

 ceptacle. But anatomy shows that this center consists of the fused 

 ventral margins of the carpels. Anatomy also shows that the carpels of 

 the Pomoideae are not adnate to a hollow receptacle. The gynoecia of 

 these taxa are "coenocarpic," not "falsely coenocarpic." 



Comparative study of the gynoecia of syncarpous taxa shows that 

 these new terms are invalid as descriptive of morphological types. It 

 may be helpful to use the adjectives paracarpous and coenocarpous to 

 describe the parts of a gynoecium that differ in structure from base to 

 tip. The term false coenocarpy is superfluous. 



Types of Carpel in Syncarpous Gynoecia. Carpels of all closing types, 

 from typical conduplicate to extreme involute (Fig. 74) and from 

 widely open to completely closed, have apparently entered into the 

 formation of syncarpous gynoecia. Union of closed carpels with lateral 

 fusion forms a multilocular, syncarpous ovary, with the placentae close 

 together at the center. The grouping of the placentae about the floral 

 axis is axile phcentation (Fig. 88A). This placentation type has been 

 generally considered the basic type, from which have been derived the 

 other types in syncarpous ovaries. The major vascular supply of the 

 typical carpel is a median (midrib) bundle, the dorsal bundle — which 

 is occasionally double — and two submarginal bundles, the ventral bun- 

 dles. In the closed carpel, the ventral bundles are inverted, in com- 

 parison with the dorsal. The inversion is brought about by the bringing 

 of the carpel margins together ventrally. 



It has been generally assumed that, in the evolution of syncarpy, 

 connation developed only among closed carpels, that the open carpels 

 of types with parietal placentation were secondarily open. But the 

 anatomy and ontogeny of many taxa — especially the Parietales and 

 others that have parietal placentation — indicate that connation took 

 place not only between closed carpels but between those that were 

 still open. The carpel at pollination time is still unsealed in members 

 of many lines and is definitely open in a few; connation, well advanced 

 in some of these lines, must have come about in open, as well as closed, 

 carpels. The variety of degree of carpel closure existing in taxa not 

 closely related suggests that connation of carpels, like other types of 

 fusion, is a general angiosperm tendency, expressed independently in 

 many lines, and that it occurred among carpels in all stages of closing, 

 even in widely open types. 



The common chamber enclosed by open carpels varies in form with 

 the degree of closure of the carpels; it is rounded in cross section where 

 the carpels are widely open ( Fig. 84£ ) , strongly lobed where the carpels 



