A polymorphic Japanese species, growing in central Honshu and extending into Shikoku and Kyushu. It is represented by many different forms and also hybridizes with other species.
According to George Schmid the holotype represents a rare form of longipes, so he named a new variety longipes var. vulgata to represent the more common type and longipes var. longipes is linked to the original and rarer type.
Other forms of this variable species:
longipes var. caduca: from Kyushu, bracts wither immediately
longipes var. lancea: has lance-shaped leaves
longipes var. latifolia: a broad-leaved form from the Izu peninsula
longipes f. hypoglauca: has glaucous leaves
longipes f. sparsa: a sparsely flowering form
longipes f. viridipes: has green petioles without purple dots
Closely related are the species aequinoctiiantha, hypoleuca, okamotoi, rupifraga.