What type of category does Echium and Oxydendrum have in common?
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.
Epidendrum flexuosum Epidendrum flexuosum, a reed-stemmed "Epidendrum" common at mid-altitudes in Central America, is a species of orchid commonly called "Epidendrum imatophyllum". It grows exposed to intense sunlight in the forest canopy, particularly on "Guava" species. "E. flexuosum" bears non-resupinate lavender flowers on a congested raceme at the end of a long peduncle.