Sunflowers are false flowers

The "flower" part of a sunflower is actually a pseudanthium: a collection of individual flowers that look like petals surrounding a disc. Sunflowers share this property with daisies, which are part of the same family.

The head of a sunflower or a daisy can also be called an inflorescence, which is the word for a cluster of flowers regardless of whether the cluster looks like a flower or not; hydrangeas and lupins also grow in inflorescences.