W. George Schmid in his
Hosta Species Update on The Hosta
Library (2007) says that "Both
H. nigrescens and H. ‘Tenryu’ have a tendency to
sport to yellow or variegated forms. A yellow form is
listed in Europe as H. nigrescens ‘Aurea’, a cultivar
name invalid according to the rules of the ICNCP and
should be called H. ‘Ogon Kuro’."
As a yellow sport of
H. nigrescens, this plant is
probably a giant size hosta with cupped foliage. The
leaves are broadly ovate shaped, moderately corrugated
and have thick substance. It has very tall (about 6 feet
high) flower scapes with pale lavender blooms
from late July into
mid-August followed by some viable seeds.
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term ogon or oogon as gold or yellow.