|Photo by Bob Wenrick|
Yesterday's bush is a creosote bush; and a good time for me to clarify something I said on a recent nature walk: the creosote used on dirt roads (for example) does not come from the creosote bush. (Thanks, Carol, for correcting me on this.)
The gall is most likely caused by a midge (according to this site):
The Creosote Gall is formed by a Midge that is in the order Diptera and is classified with the flies. The Creosote Gall is a deformation of the plant with the leaves and stems stunted to form the Gall.