A Carpel is composed of an ovary, a style and a stigma. A flower may have 1 or more carpels that collectively make up the Gynoecium, the female part of the flower. The gynoecium may be in 3 forms.

1. Monocarpous – It has  one carpel. Examples are Wild Cherry (first photo),  Common Hawthorn and most Legumes.

2. Apocarpous – It has more than one carpel but the carpels are ‘free’ as in the Hellebore (second photo) with 5 free carpels. The Buttercup and Stonecrop families have free carpels as has the Rosa and Fragaria (strawberry) genera. 

3. Syncarpous – It has more than one carpel but they are ‘united’ (sometimes called ‘fused’). The Hypericum (third photo) has 5 ‘united’ carpels with 5 free styles.  80% of flowering species have syncarpous ovaries.

 

 

Single carpel of Prunus avium Wild Cherry
5 free carpels of Helleborus niger Christmas Rose (nectaries and stamens removed)
5 fused carpels of Hypericum x ‘Hidcote’ a hybrid St John’s Wort