Is there any difference between pistil and carpel ?
• Carpels are the basic units of pistils, which may be free or fused.
• In certain situations, the two words can be used interchangeably but, in certain situations, it cannot be used so. For an example, the words are used interchangeably when a flower has three free carpels and three simple pistils. However, the two words cannot be used interchangeably when a flower has 3 fused carpels because then it contains only one compound pistil.