What is "rhizanthella"

Rhizanthella, commonly known as underground orchids, is a genus of three species of flowering plants in the orchid family, Orchidaceae and is endemic in Australia. All are leafless, living underground in symbiosis with mycorrhizal fungi. The inflorescence is a head of flowers held at, or just above the ground but mostly covered by soil or leaf litter and little is known about the mechanism of pollination.