Close-up ultraviolet photograph of a Common Daisy (Bellis perennis) flower. Under ultraviolet light the centre of the flower appears much darker than it does under visible light.
Bellis perennis is a common European species of daisy, of the Asteraceae family, often considered the archetypal species of that name. Many related plants also share the name "daisy", so to distinguish this species from other daisies it is sometimes qualified as common daisy, lawn daisy or English daisy.
Bellis perennis is native to western, central and northern Europe, but widely naturalised in most temperate regions including the Americas and Australasia.
The flowerheads are 3/4 to 1-1/4 in (approx. 2–3 cm) in diameter, with white ray florets (often tipped red) and yellow disc florets.
Although the 'flower' may appear to consist of a yellow centre with white petals, this is not the case. Each individual "petal" is itself an individual flower, called asterales. In the centre there are also many tiny yellow flowers. The different colours and styles of flower work together in order to attract insects. This type of flower is known as a composite flower.
Description adapted from Wikipedia: http://en.wikipedia.org/wiki/Bellis_perennis
Colours modified using channel mixer in PS CS5