The Hostapedia by Mark Zilis (2009), "H. 'Kofukiwa Iwa' =
H. longipes hypoglauca... the common name for
H. longipes hypoglauca, "Kofuki Iwa Gibōshi"."
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term iwa as rock, Iwa Gibōshi or
H. longipes and the term kofuki as glaucous.