Monotypic eudicot genera

Haptanthus is a monotypic genus containing the sole species Haptanthus hazlettii, a shrub or small tree known only from the locality of Matarras in the Arizona Municipality in Honduras. Its flowers are unique among the flowering plants. A single "female" (carpellate) flower has two branches on either side which carry "male" (staminate) flowers. The flowers are very simple, lacking obvious sepals or petals. The family placement of the genus has been uncertain but based on molecular phylogenetic research, it is included in the family Buxaceae . Very few individuals have ever been found, and its

Aextoxicon is a genus of dioecious trees native to southern Chile and Argentina. It is the only genus in the monotypic family Aextoxicaceae, and is itself represented by the olivillo (Aextoxicon punctatum). It is a large evergreen tree native to the forests of the Valdivian temperate rain forests and Magellanic subpolar forests of the Pacific coast of southern Chile, where it forms is a canopy tree in the broadleaf forests. It can reach 15 m tall.

Streptothamnus is a genus of flowering plants in the family Berberidopsidaceae. It has only one currently accepted species, Streptothamnus moorei, native to northern New South Wales and southeast Queensland, Australia. It is a scandent shrub found in forested montane areas.

Curatella americana, commonly known as the wild cashew tree, sambaı́ba, and the sandpaper tree, is a species of tree in the family Dilleniaceae. It is the sole accepted species in genus Curatella.