The Orchidaceae is the world's second largest and most diverse plant families, and has been estimated to contain approximately ten percent of all of the flora on Earth with some 800 named genera and a staggering 25,000+ species as well as at least 100,000+ hybrids and cultivars. Some of the genera which are best known are Paphiopedilum, Cattleya, Epidendrum, Vanda, Cymbidium, Brassia, Phalaenopsis, Spiranthes, and Dendrobium. One that many people do not realize is an orchid is the beautiful Vanilla. The Greek word orchis was first used by Theophrastes and means "testicle", from the appearance of the underground tuberous structures of the genus Orchis. The Orchidaceae is a very old family, possibly dating back to the time of the dinosaurs, but at the same time is considered by many authorities to be an advanced or highly evolved one.