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.
Catharanthus Catharanthus is a genus of flowering plants in the dogbane family, Apocynaceae. Like genus "Vinca", they are known commonly as periwinkles. There are eight known species. Seven are endemic to Madagascar, though one, "C. roseus", is widely naturalized around the world. The eighth species, "C. pusillus", is native to India and Sri Lanka. The name "Catharanthus" comes from the Greek for "pure flower".