Well, that should keep me/us busy.
I like the idea very much from the standpoint of thoroughness as well as emphasizing the individuality of each species. And as for the Euphorbias, all the species (5000 or so) have only one thing that unites them into the genus to begin with: a characteristic of the flower that is found nowhere else in the plant kingdom. So, technically, it's rather useless to have a general Euporbia parent anyway.