An article by
W.
George Schmid in The
Hosta Journal (1996 Vol. 27 No. 2) states that This is a duplicate, incorrect or outdated name for Hosta
montana 'Yae-no-Oba'.
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term oba or ooba as large leaf or 'Oba Gibōshi' which is the Japanese name for the species H. montana.