196 MORPHOLOGY OF THE ANGIOSPERMS 



with its ovules lost; several families show gradual transition from ovary 

 to style, with vestigial ovules and traces for lost ovules in the transi- 

 tional region. Elongation of the style is characteristic of many taxa. The 

 nature of the stigma is evident in the stigmatic crests of primitive 

 carpels, especially those of the woody Ranales, such as Degeneria and 

 the Winteraceae. The pollen-receiving surface of the stigma is char- 

 acteristically papillose and often secretory. Where this area extends the 

 full length of the carpel, forming an undifferentiated stigma, a stigmatic 

 crest, the papillae cover the margins of the carpel and narrow adjacent 

 bands of the lamina surface. Where the marginal areas are merely 

 approximated or appressed, the carpel still open, the papillae fill the 

 slit loosely or compactly. In some conduplicate carpels, the margins of 

 the carpels flare (Fig. 72C, F, H), exposing a narrow band of the 

 adaxial carpel surface and making the stigmatic crest two-lobed 

 (Degeneria, Drimijs). The two-lobed form of crest, conspicuous in the 

 most primitive carpels, is carried over into some advanced types and 

 doubtless explains the two-lobed stigmas of some taxa. (The double 

 lobing of stigmas of other taxa may be morphologically different.) In 

 stigmatic crests, the papillae may occur not only on the carpel margins 

 but on adjacent narrow bands of both dorsal and ventral surfaces 

 ( Degeneria, Winteraceae ) . In the Winteraceae, they may extend inward 

 on the ventral surface to the placental ridge, around the ovule bases, 

 and, in Degeneria, farther in over much of the carpel surface, forming 

 an internal continuation of the stigmatic area, even into sealed parts of 

 the carpel. A similar "internal stigma" is present in Eupomatia, where, 

 in a carpel completely closed by connation, stigmatic papillae extend 

 downward from a distal pore to and around the ovules. In the Annona- 

 ceae (Artahofrys) also, the papillate tissue extends downward along the 

 carpel margins to the ovule bases, as a transmitting tissue for the pollen 

 tubes. Internal stigmatic tissue in a sealed carpel is doubtless a remnant 

 of the more extensive stigmatic area of primitive open carpels. 



The carpel, as a simple, folded, or involute laminar appendage, with 

 several to many ovules, varies greatly in form: with or without clear 

 distinction of ovary, style, and stigma; with or without style; stipitate 

 or nonstipitate; completely or incompletely sealed. Evolutionary changes 

 in tliese characters have progressed unequally, and primitive form in 

 one character may accompany advanced form in another. The carpel of 

 this type is follicular and matures into the fruit type termed a follicle. 



Modification of the Follicular Carpel 



Specialization of the follicular carpel has been primarily in reduction 

 in size and in ovule number, simplification of vascular supply, and loss 

 of dehiscence. In extreme reduction, only one ovule persists. The fruit 



