This is one of the plants I was hoping to encounter while in California. It is relatively common, but I had never seen it before, so it was new to me.
Castilleja exserta (also sometimes called Orthocarpus purpurascens) is native to the southwestern US and northern Mexico. Common names include exserted Indian paintbrush, purple owl’s clover, and escobita. Occasionally, it can be found en masse, carpeting the grassy terrain it grows in with purple. However, I only observed a few individuals here and there, with the exception of one small knoll that was covered in plants. Unfortunately, it was fenced off and so didn’t permit a closer look.
Calflora.net has a good summary of the properties of Castilleja exserta, as well as additional photographs. Even more photographs are available via CalPhotos. The Jepson Manual treatment of Castilleja exserta makes mention that the species is “highly variable” and often hybridizes. Lastly, the Pima County Master Gardeners give a few growing tips for those of you interested and in areas where it can be grown.