What type of category does Echium and Oxydendrum have in common?
Echium Echium is a genus of 60 species of flowering plant in the family Boraginaceae.
Erythroxylum Erythroxylum ("Erythroxylon") is a genus of tropical flowering plants in the family Erythroxylaceae. Many of the approximately 200 species contain the drug cocaine; "Erythroxylum coca", a native of South America, is the main commercial source of cocaine and of the mild stimulant coca tea. Another species, "Erythroxylum vacciniifolium" (also known as Catuaba) is used as an aphrodisiac in Brazilian drinks and herbal medicine.