Orchids are a diverse family (Orchidaceae) of perennial plants highly valued in the florist industry for their striking, exotic flowers. Their common name stems from the Greek word orchis, meaning "testicle", which is suggestive of the shape of the root tubers some members of the family develop. The roots of a number of orchid species have a symbiotic relationship with specialized fungi, and the tiny seeds of the plants require interaction with fungi to germinate naturally. More than 15,000 orchid species are recognized, most of which inhabit tropical regions, though some can be found in nearly all nonpolar locales. In several areas, rare orchids that garner particularly high prices have been collected to such a great extent that protections have been put in place to save them from extinction.