The Yellowstone Resources and Issues Handbook, updated annually, is the book our rangers use to answer many basic park questions.
Craighead, J.J. et al. 1963. A Field Guide to Rocky Mountain Wildflowers from Northern Arizona and New Mexico to British Colombia. Boston: Houghton Mifflin.
Cronquist et al. (ongoing, currently 6 volumes) Intermountain Flora. New York Botanical Garden.
Despain, D. 1990. Yellowstone Vegetation: Consequences of Environment and History in a Natural Setting. Boulder: Roberts Rinehart.
Dorn, B. 2001. Vascular Plants of Wyoming. 3rd edition.
Elliot, C.R. and M.M. Hektner. 2000. Wetland Resources of Yellowstone National Park. YNP: Wyoming. (2.8 MB PDF)
Hitchcock and Cronquist. 1974. Flora of the Pacific Northwest. Seattle: UWashington Press.
Hitchcock et al. Vascular Plants of the Northwest (5 volumes). Seattle: UWashington Press.
Kershaw et al. 1998. Plants of the Rocky Mountains. Lone Pine Publishing.
Preston, R.J. 1968. Rocky Mountain Trees: A Handbook of the Native Species with Plates and Distribution Maps. New York: Dover.
Romme, W.H. and . Knight. 1982. Landscape diversity: The concept applied to Yellowstone National Park. Bioscience. 32:8.
Shaw, R.J. 1964. Trees and Flowering Shrubs of Yellowstone and Grand Teton national parks. Salt Lake City: Wheelwright Press.
Shaw, R.J. 1992. Wildflowers of Yellowstone and Grand Teton national parks. Salt Lake City: Wheelwright Press.