are Cladanthus and Oxydendrum both plant genus ?
Oxydendrum Sourwood or sorrel tree, Oxydendrum arboreum, is the sole species in the genus Oxydendrum, in the family Ericaceae. It is native to eastern North America, from southern Pennsylvania south to northwest Florida and west to southern Illinois; it is most common in the lower chain of the Appalachian Mountains. The tree is frequently seen as a component of oak-heath forests.
Orectanthe Orectanthe is a genus of flowering plants, in the family Xyridaceae, first described as a genus in 1958. It is native to the tepui of northern South America (Venezuela, Guyana, and northwestern Brazil). It is closely related to "Abolboda", and both known species were originally classified as members of "Abolboda" before being transferred to "Orectanthe".