For a list of the plants and animals known to occur in a national park or monument, go to https://irma.nps.gov/NPSpecies/
At this website, choose, for example, Devils Tower National Monument, if interested in this area, and then, under Category, select the category of interest. Then select Full List with Details. For plants, herbarium images can be viewed by clicking on External Links. Checklists can be produced using the Reports tab near the top of the page. For assistance, use the Help option.
Well illustrated field guides to the flora of Wyoming and the region are commonly found in local bookstores. Some focus on the plants of specific areas, such as the Black Hills, and Yellowstone and Grand Teton National Parks. Most focus on plants with distinctive flowers. Deciding on which wildflower guide to use is a matter of personal preference.
Four of the more detailed books commonly used by Wyoming botanists are:
Dorn, R. D. 2001. Vascular Plants of Wyoming (3rd edition). Mountain West Publishing, Cheyenne, Wyoming.
Nelson, R. A. (revised by Roger L. Williams). 1992. Handbook of Rocky Mountain Plants. Roberts Rinehart Publishing, Niwot, Colorado.
Skinner, Q. D. 2010. A Field Guide to Wyoming Grasses. Education Resources Publishing, LLC, Cumming, Georgia.
Whitson, T. D., ed. 2000. Weeds of the West (9th edition). Western Society of Weed Science, Newark, California, in cooperation with the Western United States Land Grant Universities Cooperative Extension Services.