THE CARPEL 



205 



from two lateral areas. Two-lobed form ( Fig. 80C, D, E ) may give evi- 

 dence of this union, but often the fusion is anatomically complete and 

 the placenta is simple in form and structure. It has been suggested 

 that the term half placenta be used for each of the parts of this double 

 structure, but this would involve unnecessary complications in descrip- 

 tion, especially in syncarpy, where fertile areas from adjacent carpels 



Fig. 80. Chart showing placentation in the Gentianaceae. The variety of types show 

 theoretical modifications of basic form and possible evohitionary relationships of 

 types. Placenta merely a position in A, F, I, J- a ridge in H; a carpellary flange in 



B, C, D, E, G. A, Gcntiana chinensis; B, Chironia baccifera; C, C. palustris; D, 



C. dcnsiflom; E, Sabatia; F, Crawfordia fasciciilata; G, Bartonia virginica; H, 

 Frascra speciosa; I, Gentiana linearis; ], G. crinita. {After Lindsey.) 



unite to form a common placenta. Placentae would have to be described 

 —as were carpels under the polymorphism theory — as "one-half plus 

 one plus one-half" in nature. The term placenta should be used loosely 

 for the fertile area of a carpel or united carpels. 



Types of Placentation. In both morphology and taxonomy, the use of 

 terms describing placentation is inconsistent and confused. A term given 

 to placentation in free carpels has been applied to a morphologically 

 different type in connate carpels. And differences in interpretation of the 

 nature of the syncarpous gynoecium — whether it is wholly carpellaiy or 



