There are two kinds of carpels in the Cruciferae; a valve, or "sterile" carpel, and a "solid" or "fertile" carpel. These carpels are arranged in two whorls of two carpels each. The outer whorl is made ...

Ammonite types with typical swirls are called “regular whorls,” while the types with straight lines without any spiral features or other special patterns are called “irregular whorls.” ...

three different flower types are distinguished: the marginal ray flowers, the intermediate trans flowers, and the central disc flowers. In each flower type, all basic four whorls of floral organs are ...