⚠ Version 1 of The Plant List has been superseded.
This name is in version 1.1 of The Plant List, record tro-29204279, with some changes.
This name is a synonym of Penstemon rydbergii var. aggregatus (Pennell) N.H. Holmgren.
The record derives from Tropicos which reports it as a synonym (record 29204279) with original publication details: Contr. U.S. Natl. Herb. 20(9): 367-368 367 1920.
Full publication details for this name can be found in IPNI: urn:lsid:ipni.org:names:187125-2.