It was thought for many years to contain only one species, Geosiris aphylla, endemic to Madagascar.

But then in 2010, a second species was described, Geosiris albiflora, from Mayotte Island in the Indian Ocean northwest of Madagascar.

It is a small myco-heterotroph lacking chlorophyll and obtaining its nutrients from fungi in the soil.

In 1939, F. P. Jonker[5] assigned Geosiris to its own family Geosiridaceae in Orchidales, and this was adopted in the Cronquist system,[6] with a note that the family was closely related to Iridaceae or Burmanniaceae.

The Angiosperm Phylogeny Group has since subsumed the family into Iridaceae; it is currently placed in the monotypic subfamily Geosiridoideae.