Rose petal. Coloured scanning electron micrograph (SEM) showing papillae on the petal of a Garden Rose flower, Rosa sp. Papillae are projections from epidermal cells. They are often swollen and covered in wax to help reduce water loss by the flower. Brightly coloured petals in a flower serve as visual attractants to pollinators; rose plants rely on insect pollinators to spread the male pollen to the female stigmas of the flower. The rose flower has been grown and appreciated for its fragrance and beauty since ancient times, and today is the most popular and widely cultivated garden flower in the world. Magnification: x700 at 6x9cm size magnification: x2,300 at 12x28 size.