Not an accepted name (status: rejected). The accepted name is Caltha biflora DC., 1817.

Caltha leptosepala subsp. howellii (Huth) P.G.Smit, 1817 16% complete

No common name

Syst. Nat. 1: 310 (1817)

There is no corrections for Caltha leptosepala subsp. howellii yet.