This is Keckiella antirrhinoides (chapparal beard tongue or desert bushpenstemon) from Cactus Spring Trail in Riverside County. It's the host there of Euphydryas chalcedona hennei.

Larval nests of Euphydryas chalcedona hennei on the Keckiella at Cactus Spring Trail, Santa Rosa Wilderness, May 30, 2010.

In the Kingston Range, there is a canyon 3/4 of a mile as the crow flies from Horse Thief Spring that is the type locality of Euphydryas chalcedona kingstonensis. I knew I found the canyon when I found the plant, and it was remarkably large compared to what I'd seen elsewhere.

Note the "beard tongue".

This was in the Kingston Range as well as below.

When I first saw these large shrubs from a distance I thought they were the largest sennas I'd seen, but on closer inspection I realized what they were. And soon, I found the butterfly I wanted. This was late April, 2020.