It seems that Nijiseiki (20th century) figures prominantly in the parentage of many Japanese pears available in the U.S. I wonder what that means about the genetic diversity of the commonly available cultivars. Just got me interested in constructing a "family tree" for my Japanese pears, but I'm missing some information. Does anyone know the parental history of the following: Meigetsu; Yoinashi (and does this have an older cultivar name?); Yongi?