ANGIOSPERMS 



227 



ovules are exposed on the surface of the carpel, while in 

 the Angiosperms they are enclosed by the carpel as in a 

 closed vessel. Gymnosperm means "seed naked/' and 

 Angiosperm means "seed in a vessel "; hence the names of 

 the groups refer to this difference in the carpels. 



The carpel of an Angiosperm flower has the general 

 shape of a flask (Figs. 207 and 215, A). The bulbous 

 bottom in which the ovules are enclosed is called the ovary; 

 the neck of the flask, which may be short or long, is called 

 the style; and upon the style, either on its top, which is 

 often knob-like, or along its side, there is a specially pre- 

 pared surface to receive the pollen, known as the stigma. 

 This stigmatic surface, when ready to receive the pollen, 

 is sticky; the style, unlike the neck of a flask, is usually 

 solid; so that the ovary is the only part of the carpel that is 

 hollow. The ovules in an ovary vary in number from a 

 single one to a great 

 number, and they are 

 borne in a variety of 

 positions on the inner 

 wall of the ovary. 



In many flowers 

 the carpels remain 

 separate (Figs. 207 

 and 215, A), as in 

 the buttercups ; but 

 it is very common for 

 all the carpels of a 

 flower to unite in the 

 formation of a single 

 structure, whose general outline is that of a single car- 

 pel. That is, it has a single ovary and may have a single 

 style (Figs. 208, C, and 215, C). It is convenient to have a 

 word to apply to this ovule-containing structure, whether 

 it consists of one carpel or of several organized together, 



FIG. 215. A, simple pistils (each one a single 

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

 composed of several carpels). After BERG 

 and SCHMIDT. 



