Orchid flowers (Catasetum fibriatum). One of the petals (white) on each flower is a specialised structure called a lip. This attracts pollinators to the flower, and acts as a landing platform. This is an epiphytic orchid (one that grows in trees). It is found in tropical South America. There are more than 30,000 species of orchids worldwide, many of which are grown as ornamental flowers.