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.
History of Pachypodium The history of the genus Pachypodium as a scientific classification began in 1830, when the genus was first used in a taxonomical system by John D. Lindley, who placed a single species, "P. tuberosum", in it. Lindley believed that this species was identical with one identified in 1781 as "Echites succulenta", which would make "Pachypodium" a taxonomical synonym of "Echites".