This form of
was first described by
Dr. Fumio Maekawa around 1940. It has narrower flower petals and corolla
than the species or H. plantaginea
The Hostapedia by Mark Zilis (2009), "Schmid 1991, p. 85) reduced this to cultivar status,
i.e., H. plantaginea 'Stenantha'; though I do not
agree with his assignment."