Orchid, 2004
Photograph by Robert Clark
For legendary 19th-century scientist Charles Darwin, orchids, like the dew-beaded beauty shown here, epitomized the theory of natural selection, the belief that plants and animals evolve with traits favoring survival and reproductive success. By this measure orchids are a sensational success, with 24,000 species and 60,000 registered hybrids, far more than any other flowering plant on Earth.