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A TEXT-BOOK OF BOTANY 



and such a word is pistil. A pistil, therefore, is any organ- 

 ization of carpels that appears as a single organ with one 

 ovary. A pistil composed of one carpel is called a simple 

 pistil (Figs. 207 and 215, A), and one composed of more 

 than one carpel is a compound pistil (Figs. 208, C, and 215, 

 C). When a flower has one pistil, it is necessary to dis- 

 cover whether it is a simple or a compound pistil, and if it 

 is the latter to determine the number of carpels that enter 

 into its structure. Sometimes the styles are separate 

 (Fig. 215, B), or the single style is cleft more or less deeply; 

 and in either case the answers to both questions are very 

 apparent. But often the style is single throughout and 

 does not indicate the number of carpels. In that case the 

 ovary must be cross-sectioned, and if the section reveals 

 more than one ovule chamber the compound character 

 and the number of carpels are usually apparent (Fig. 216, 

 B). Sometimes, however, a compound ovary may have 

 only one ovule chamber, and in this case the number of 



A B 



FIG. 216. Diagrammatic cross-section of compound ovaries: A, a one-charnbered 

 ovule composed of three carpels; B, a three-chambered ovule. After SCHIMPER. 



carpels may be indicated by the number of rows of ovules 

 on the wall (Fig. 216, A). 



It is necessary to know something about the structure 

 of the Angiosperm ovule (Fig. 217). That it is a sporangium 

 containing one large spore (megaspore) that is never shed, 

 was pointed out in connection with the Gymnosperms 



