A previous edit (and some other entries referencing this) misinterpret the section on the "stem" nature of the Usher family. It specifically mentions the patrimony being handed down from son to son so that the physical "house" and the figurative "house" of the family tree are one and the same. This is not a matter of Usher's marrying each other, females would not carry the family name. It is that there have not generally been multiple sons per generation splitting the family into different branches, and during those infrequent times that did occur the other branches died out.
A previous edit (and some other entries referencing this) misinterpret the section on the "stem" nature of the Usher family. It specifically mentions the patrimony being handed down from son to son so that the physical "house" and the figurative "house" of the family tree are one and the same. This is not a matter of Usher's marrying each other, females would not carry the family name. It is that there have not generally been multiple sons per generation splitting the family into different branches, and during those infrequent times that did occur the other branches died out.