138 



ELEMENTARY STUDIES IN BOTANY 



megasporophyll among Pteridophytes ; tnat is, the carpel 

 is a megasporophyll. It has been stated also that the angio- 

 sperm carpel differs from that of the Gymnosperms in in- 

 closing the megasporangia (ovules), the number inclosed 

 ranging from one to very many. 



In forming a case about the ovules, two regions of the car- 

 pel usually become evident (Figs. 102, C, and 110) : (1) a more 

 or less bulbous region that incloses the ovules (the ovary), 



and (2) a more or less 

 extended beak-like re- 

 gion arising from the 

 ovary (the style) . The 

 name ovary was given 

 ^vvhen the ovules were 

 thought to be eggs, 

 and both names are 

 unfortunate, for they 

 imply what is not true, 

 but they have been 

 used for so long a time 

 that it would be more 

 confusing to replace 

 them than to retain 

 them. The significance 



of the style is found in the fact that it provides a special re- 

 ceptive surface (the stigma) for the pollen grains, and the 

 length and form of the style are answers to the problem of 

 the most favorable position for the stigma. Very commonly 

 the style swells into a knob at the top, and the surface of this 

 knob is the stigmatic surface (Figs. 102, C, and 110, C). 

 Sometimes the stigmatic surface extends down the side of 

 a style, as in corn, in which the so-called " silk " is made up 

 of styles (Figs. 109, and 110, B). Rarely, there is no style 

 at all, and the stigmatic surface is upon the ovary itself. 

 It is evident, therefore, that the two essential features of an 



FIG. 110. A, simple pistils (each one a single 

 carpel) ; B and C, compound pistils (each one 

 composed of several carpels) ; in B the stigma 

 extends along the sides of the styles, in C it is 

 on the terminal knob of the style. After BERG 

 and SCHMIDT. 



