Stem

• The stem of a flower is called a floral axis. Crowning the floral axis is what we think of as the flower, this possessing one to four parts arranged in whorls.
  
  

Calyx

• Traveling up from the floral axis, we find the calyx, the outside whorl of the flower. The calyx has a number of sepals. The calyx protects the bud of the flower before it blooms.
  
  

Corolla

• The corolla is the next whorl as we move inward in the flower. It's comprised of petals, which can have organs to produce the nectar that insects are attracted to. The corolla and calyx are together known as the perianth.
  
  

Androecium

• The next whorl in finds the male part of the plant called the androecium. The androecium consists of the stamens, which make pollen. A stamen is a filament topped by the anther.
  
  

Gynoecium

• The last whorl is the gynoecium, which is the female part of the plant. It is formed of a carpel, alternatively termed a pistil, or carpels. The carpel consists of the style (with the stigma at its tip to receive pollen), the ovary and ovules, which have to be pollinated to produce seeds.