THE CARPEL 



243 



Achhjs (Fig. 76E), Cocos, and related genera. The vestigial carpels of 

 the coconut merge into the common ovary wall — the "shell" of the 

 coconut; and the position of the obliterated loculi is evident by com- 

 pressed tissue (Fig, 93). This is evidence that the shell consists, mor- 

 phologically, of the inner wall layers of a compound ovary, and is not 

 the seed coat, as often described. Reduced carpels of the Cruciferae 

 and some of the Papaveraceae ( Fig. 76C ) and Capparidaceae are struc- 

 turally solid, though not commonly accepted as such. Evidence that 

 these are "solid," in the morphological sense of loss of locule, not in 

 the sense of the polymorphism 

 theory, is in their vascular supply 

 and in comparison of the gynoecia 

 of these families. Accessory styles 

 and stigma lobes may be external 

 evidence of greatly reduced carpels. 

 Evidence of carpels completely lost 

 from the ovary may be present as 

 vestigial vascular traces in the re- 

 ceptacle leading to the position of 

 the lost organs — Degeneria, Cimici- 

 fiiga. 



Style and Stigma in Syncarpous 

 Gynoecia. Connation among carpels 

 may extend from base to tip or for 

 only part of their length. Fusion by 

 ovaries alone is common; that by 

 proximal parts only of the ovaries is 

 frequent. Fusion by stigmas alone is 



rare — Apocynaceae, Asclepiadaceae, Rutaceae, Simarubaceae. Free styles 

 and stigmas often form a prominent part of syncarpous gynoecia. Fusion 

 may be ontogenetic or congenital, or the distal fusion ontogenetic and 

 the basal congenital. 



Stigma form, where carpels are united, is, of course, related to num- 

 ber and intimacy of fusion in the uniting stigmas. Interpretation of 

 carpel number in a syncarpous gynoecium is often based on number of 

 lobes of the compound stigma, but this basis is unsound. The stigma of 

 the free carpel may be simple or lobed, and, in reduced gynoecia, the 

 number of stigmas is often less than that of the carpels present. 

 Highly specialized stigmas — globose, cylindrical — may give no evidence, 

 external or internal, of their compound nature; only stiucture of the 

 ovary can determine this. Simple stigmas are not necessarily primitively 

 simple. 



Where, in syncarpous gynoecia, the number of carpels is two or three 



Fig. 93. Cross section of ripe "nut" of 

 Cocos nucifera, showing at C, C rem- 

 nants of the locules of the two sterile 

 carpels embedded in the inner ovary 

 wall ("shell"). 



