⚠ Version 1 of The Plant List has been superseded.
This name is in version 1.1 of The Plant List, record tro-50104107, with some changes.
This name is a synonym of Penstemon cardinalis subsp. regalis (A. Nelson) G.T. Nisbet & R.C. Jacks..
The record derives from Tropicos which reports it as a synonym (record 50104107) with original publication details: Amer. J. Bot. 21(9): 578-579 578 1934.
Full publication details for this name can be found in IPNI: urn:lsid:ipni.org:names:187730-2.