THE CARPEL 187 



stipe is sometimes confused with the gynophore, an elongate part of the 

 receptacle that bears the entire gynoecium. Anatomy shows that the 

 stipe is a part of the carpel, not of the receptacle; the vascular traces of 

 the carpel arise from the receptacular stele and are independent in the 

 stipe, with the ventral traces inverted (Coptis, Tofieldia). Stigma, style, 

 and ovary are parts of the lamina of the sporophyll, functionally dis- 

 tinct but often merging. The style, in some taxa, represents a sterile 

 part of the ovary; in other taxa, it seems to be formed by a secondary 

 elongation of the distal part of the carpel. 



The carpel varies from simple, without differentiation into fertile 

 and sterile parts, to complex. The complex form is divided into a 

 proximal, ovule-bearing part, the ovary; a distal, pollen-receptive part, 

 the stigma; and a median sterile section, the style. Usually terminal on 

 the ovary, the st)'le appears to be lateral in some highly specialized 

 taxa — the Labiatae and achene types in the Rosaceae ( Potentilleae, 

 Chrysobalanoideae). In these plants, ontogeny and the course of the 

 midrib bundle show that the lateral position is secondary. The st\'le is 

 terminal in early stages, but growth of the ovule and seed on the dorsal 

 side displaces the style. The style appears nearly basal, seeming, in 

 later stages, almost independent of the carpel. But anatomy shows that 

 the dorsal bundle of the carpel is continuous from the base of the 

 carpel over the ovule — along the dorsal side and top of the enlarged 

 ovule-bearing base, down to the base of the st^-le and upward through 

 the style. Obviously, the two structures are parts of one organ. (Under 

 the carpel polymorphism theory, the two parts of the carpel were in- 

 terpreted as two independent organs — one solid, the style, and one 

 valvular, the ovary.) 



The carpels of some of the woody Ranales illustrate the simple type 

 (Fig. 72). They are elongate, usually without distinction of ovary, style, 

 and stigma. The many ovules are borne throughout an elongate cham- 

 ber. The pollen in many is received on a longitudinal stigmatic crest 

 (Fig. 72C, F, H, I), consisting of the papillose surfaces of the margins 

 and borders of the lamina, which have come together in the closing of 

 the carpel. The double nature of the crest is evident in its more or less 

 strongly two-lobed form, the margins flaring back somewhat from the 

 line of contact (Fig. 72F, H). In some species of Drimys, in Hi7nan- 

 tandra and Degeneria (Fig. 83A, B), the crest extends from the apex to 

 the base of carpel (taxonomic descriptions read "stigma decurrent"); in 

 other taxa, it is restricted to the distal part (Fig. 72D, E, H, I). In 

 these primitive taxa, the marginal areas of the lamina are appressed 

 but not fused histologically; closure of the carpel is by interlocking of 

 projecting papillae. The pollen germinates on the stigmatic crest over 

 its full length, and pollen tubes may penetrate directly to the nearest 

 ovules. Elongate stigmas may represent primitive form, as in many 



