- Divided into, or consisting of, five parts; also,
arranged in sets, with five parts in each set, as a flower with five
sepals, five petals, five, or twice five, stamens, and five pistils. - Belonging to the Pentamera.
Meaning of 'pentamerous' (Princeton's WordNet)
1 . pentamerous
[ s]
Meaning (1): - divided into five parts; specifically, having each floral whorl consist of five (or a multiple of five) members