There are many different kinds of dahlias. Some are like globes and some are flat faced. The number of petals is a Fibonacci number.
http://www.popmath.org.uk/rpamaths/rpampages/sunflower.html
Normally it has 6, but it can have 12.
How many petals do dhalia have
Dahlia is a dark leafed single dahlia It is a very vibrant pink-purple. As a single dahlia, it has only one row of petals.
Dahlias often have a great many more than eight petals. They do have eight sets of homologous chromosomes which is why there are so many thousands of different dahlias.
Dahlias have a variety of types. Some have a single row of petals. Some have many rows of petals that form a globe. Some have more spiky petals. The blooms vary in size from 3 inches to 12 inches.
The blue bayou dahlia grows to about 4 feet high. It has a blue lavender set of outer petals and a darker lavender pin cushion center.
21 petals
42 petals
100 petals
Lilacs have four petals but there are double lilacs with eight petals.
It may have as many as 40 petals.
There are many types of peonies and they have different numbers of petals. Single peonies have between 5 to 12 petals. Other peonies have multiple rows of petals.
Euphorbia flower does not have petals.
An African violet has five petals.