Not a lot to go on, so I can't really say with certainty...but based on familiarity with the CA flora and leaf gestalt (e.g. texture, margin, fine-puberulence/glandularity) my best guess for the plant here is:

          Salvia mellifera...also known as "black sage"...in the mint family (Lamiaceae).

Compare with the leaf images here...click the thumbnails to enlarge, and for more detail zoom-in by pressing "cntl+" (on Windows computers) or "cmd+" (on a Macintosh).

I'm guessing Andy may be familiar with this plant...it's a dominant member of the chaparral community along much of Hwy 33. (Here's a link to the CCH record closest to Holiday Group Campground.)

Another possibility is Lepechinia calycina...but its leaves are typically wider & a bit more pubescent than in Andy's photo. Note it's also in Lamiaceae, and the locale here is at the southeast edge of its range.

PS: Regarding plant relationships for Closterocoris amoenus, please see my comment here...where the bush monkeyflower, mint & mallow families figure.

Please disregard...can't delete these inadvertent comment errors!