Monotypic Dioscoreales genera

Lophiola is a genus of monocotyledonous flowering plants native to eastern North America. It has variously been placed in the Liliaceae, the Haemodoraceae, the Tecophilaeaceae or the Nartheciaceae.

thumb|left|Diagram of Dictyostega flower

Relictithismia kimotsukiensis is a species of fairy lanterns. It is placed either in the family Thismiaceae, or in the family Burmanniaceae by those who do not recognize Thismiaceae. It is the only species in the genus Relictithismia. This mycoheterotrophic plant is known only from the Kimotsuki Mountains, in the Ōsumi Peninsula, Kagoshima Prefecture, Kyushu Island, in the southern Japan. The species is assessed as Critically Endangered based on IUCN Guidelines.

Marthella is a genus of flowering plants in the Burmanniaceae, first described as a genus in 1903. It contains only one known species, Marthella trinitatis, endemic to the Island of Trinidad. It is considered critically endangered and only naturally appears in Northern Range Forest Reserve Section B. As a conservation measure, it is being cared for in the Heights of Aripo Village as a form of ex situ conservation.