THE CARPEL 231 



Syncarpy 



Connation of carpels is a prominent feature in the specialization of 

 the gynoecium and is found in great variety of position and extent of 

 fusion. Degree and type of closure of the individual carpels that enter 

 into the compound structure increase the complexity of syncarpous 

 gynoecia. These gynoecia are often difficult to interpret when the fusion 

 is intimate, involving the vascular tissue, and reduction has occurred. 

 But all gynoecia are interpretable in terms of the simple, free carpel 

 when ontogeny, vascular structure, comparison with gynoecia of related 

 taxa, and the modifications that commonly accompany reduction are 

 considered. Syncarpy has arisen independently in many taxa, and differ- 

 ent degrees of fusion may occur within a genus. 



Connation may occur among any number of carpels and among those 

 arranged in spirals, as well as in whorls. It is infrequent among spirally 

 placed carpels — the Annonaceae, Eupomatiaceae, Zygogymim, some 

 Berberidaceae. In spiral arrangement, adjacent carpels meet at different 

 levels; the base of the ovary of one carpel may be fused with the top of 

 the ovary of another. Fusion among carpels is primarily by the sides 

 (dorsal surface) of the folded or inrolled laminae; infrequently, it is 

 by the ventral margin only. It is seen in all degrees of histological union 

 and longitudinal extent. The union may be throughout carpel length, 

 by the base or apex only, by the middle only (rare), or by both apex 

 and base, with the carpels free in the central region; it may involve the 

 entire lateral walls, or only parts of them — the margins, median or 

 distal strips. The form of the individual carpel and its primordium — 

 crescent-shaped or tubular — controls, in part, the area of contact be- 

 tween them. Ovaries, styles, and stigmas are involved where fusion is 

 throughout the length of the carpels; where it is incomplete distally, 

 styles and stigmas are free. (The number of styles and stigmas does 

 not necessarily indicate the number of carpels involved in the fusion.) 

 When fusion is at the base only and is of slight vertical extent, the 

 gynoecium may appear apocarpous — Butomus, Scheuchzeria, Spiraea, 

 Aquilegia. (For all taxonomic uses, it can be so called.) Fusion by 

 stigmas only, as in the Asclepiadaceae and Apocynaceae, is rare. Fusion 

 among the units of the syncarpous gynoecium is congenital in most 

 taxa. It may be, in part, ontogenetic; the distal parts of the carpels may 

 arise from separate primordia and, all the primordia later uniting, form 

 a ring-shaped meristem which develops the basal part. 



Carpels adnate laterally to the receptacle have been described as 

 forming a false syncarpous gynoecium; if the carpels are also connate, 

 the gynoecium is truly syncarpous. Some so-called false syncarpous 

 gynoecia have been misinterpreted, as in Nigella, where the central 



