The Intermountain Region Herbarium Network has a fairly comprehensive inventory of plant species found in all areas where you'll be working, including an image library and a key.
The Jepson Herbarium is a great resource for videos outlining plant families you may encounter in the field.
The Calflora app has created a useful database if you need a refresher on botanical terminology.
When in the Field, Nevada Wildflowers is a very helpful app to have on hand for quick plant ID.
Before the season starts, you will receive botany and plant identification training from GBI. Each crew will be issued a copy of a relevant flora as well as botanical reference books. But it never hurts to familiarize yourself with what you might encounter ahead of time.
In addition, GBI has developed lists of common plants and field guides for Nevada, California, Oregon and Colorado which may be useful references.
Check them out below, in addition to the following key to families of vascular plants!