Orchid flower (Dimerandra emarginata). The white and pink petal (lower right) is called the lip, a specialised petal that attracts pollinators and provides them with a landing platform. The Dimerandra orchids grow in trees (they are said to be epiphytic) in the dry lowland forests of tropical America. This specimen is from Venezuala. There are more than 30,000 species of orchids worldwide, many of which are grown as ornamental flowers.