Grindelia rubricaulis var. robusta (Nuttall) Steyermark

Grindelia rubricaulis var. robusta (Nuttall) Steyermark is a synonym sensu Bartoli & Tortosa, 2012 of:

Grindelia humilis Hooker & Arnott var. humilis, an accepted variety name sensu Bartoli & Tortosa, 2012.