Orchid flowers (Encyclia brassavolae, also known as Panarica brassavolae). One flower is seen in the foreground with others behind it. The flower has a specialised petal called the lip (here it is white). The other two petals and the three sepals are long and thin and form a distinctive star- shaped structure. The lip attracts pollinators to the flower and provides them with a landing platform. This orchid is found growing in trees (it is said to be epiphytic) in tropical Central America. There are more than 30,000 species of orchids worldwide, many of which are grown as ornamental flowers.