Hint: Petals are modified leaves that surround a flower's reproductive parts. To attract pollinators, they are frequently brightly coloured or unusually shaped. All of a flower's petals are referred to collectively as the corolla.
Complete answer: A flower is a reproductive structure found in flowering plants. It is also known as a bloom or blossom. A flower's biological function is to aid reproduction, typically by providing a mechanism for the union of sperm and eggs.
A flower's essential parts are divided into two categories: the vegetative part, which consists of petals and associated structures in the perianth, and the reproductive or sexual part. A stereotypical flower is made up of four different types of structures that are attached to the tip of a short stalk. On the receptacle, each of these types of parts is arranged in a whorl.
Pentamerous flowers are those that have five members that are divided into five parts and are arranged in sets of five sepals, five petals, five, or twice five, stamens, and five pistils. The Apocynaceae is a family of trees, shrubs, and herbs with milky sap. The flowers are actinomorphic and bisexual. The corolla is 5-lobed and sympathetic. They usually have five petals that are joined together at the base to form a tube. As a result, it is a pentamerous flower.
Thus, there are 5 petals or their multiples are found in pentamerous flowers.
Note: Sunflowers are members of the genus Helianthus, which contains numerous species. Helianthus annuus is the common sunflower, which is grown for its edible oil. Flowers are classified as trimerous, tetramerous, or pentamerous based on the number of floral appendages present (3, 4, or 5). The sunflower is a pentamerous flower with five or more petals.