An article by W. George Schmid in
Hosta Journal (1985 Vol. 16) discusses the
University of Munich's trial gardens named Staudensichtungsgarten Weihenstephan, "...a
fine collection of hostas. These are of great importance from a historical
standpoint, because many of the cultivars there came from the early German
hybridizers, including Georg Arends. They include
H. sieboldii (syn. H. albomarginata) 'Alba Improved',
H. ventricosa 'Superba', H. tardiflora 'Hybrids'
and H. 'Elegans'."
would suspect that this is a sport of Hosta sieboldii
but...we don't know for sure.