198 



MORPHOLOGY OF THE ANGIOSPERMS 



form a pollen-receptive area, which is doubtless the primitive stigma. 

 Restriction of the crest to its distal part, with reduction and sharper 

 delimitation, has formed the specialized stigma of the higher taxa. In- 

 termediate forms occur — Butomus, Calfha, TroUiiis. Some decurrent 

 stigmas are probably specialized, rather than primitive, types, as in 

 anemophilous taxa — Cercidiphijlhtm (Fig. 146), Juglandaceae, Thalic- 

 trum, some Restionaceae (Anarthria). 



Fig. 76. Semisolid and solid carpels in syncarpous gynoecia. A, B, Glaucium flavum; 



C, Chclidonittm majus, one of die two pairs of carpels without loculus, one carpel 

 showing ovules; D, Valeriana sp., two solid carpels, each with vestigial loculus and 

 one normal carpel; E, Aclihjs sp., two carpels, one fertile and one solid (without 

 loculus); F, Triglochin palustris, three normal, three solid carpels; G, T. maritima, 

 six normal carpels; H, Triostcinn po-foliatiim, three normal carpels with large loculi, 

 one solid, sterile, with narrow loculus; /, Linnaea borealis var. americana, three 

 carpels with two adnate bracts, one normal, two solid. (A, B, C, after Van Tieghem; 



D, after Dijal; E, after Chapman; F, G, after Uhl; H, I, after Wilkinson, 1949.) 



The stigma and the conducting tissue — much better termed the 

 transmitting tissue, because vascular tissue is commonly called the con- 

 ducting tissue — represent the surviving and specialized parts of the 

 stigmatic crest and the accompanying papillose carpel surface, which, 

 in primitive carpels, extended between the carpel margins, over their 

 internal surface, about the ovules, and even farther in on the laminar 

 surface. In carpels with a stigmatic crest, the pollen tubes pass directly 

 to ovules that are close to the place of germination. Restriction of the 



