Alpine Plants of North America: An Encyclopedia of Mountain Flowers from the Rockies to Alaska. 2002. Graham Nicholls. Timber Press.

American Azaleas. 2004. L. Clarence Towe. Timber Press.

Bulbs of North America. 2001. Jane McGary. Timber Press.

The Cactus Family. 2001. Edward F. Anderson. Timber Press.

Calochortus: Mariposa Lilies and Their Relatives. 2007. Mary E. Gerritsen & Ron Parsons. Timber Press.

Carnivorous Plants of the United States and Canada. 2nd ed. 2002. Donald E. Schnell

Ceanothus. 2006. David Fross & Dieter Wilken. Timber Press.

Columbines: Aquilegia, Paraaquilegia and Semiaquilegia. 2003. Robert Nold. Timber Press.

Flora of North America North of Mexico [online]. Flora of North America Editorial Committee, eds. 1993+. 16+ vols. New York and Oxford. Vol. 1, 1993; vol. 2, 1993; vol. 3, 1997; vol. 4, 2003; vol. 5, 2005; vol. 7, 2010; vol. 8, 2009; vol. 19, 2006; vol. 20, 2006; vol. 21, 2006; vol. 22, 2000; vol. 23, 2002; vol. 24, 2007; vol. 25, 2003; vol. 26, 2002; vol. 27, 2007. Flora of North America website.

Field Manual of Ferns and Fern Allies of the United States and Canada. 1985. David B. Lellinger. Smithsonian Institution Press.

Flowering Plant Families of the World. 2007. V. H. Heywood, R. K. Brummit, and A. Culham. 2007. Flowering Plant Families of the World. Firefly Books.

Lewisias. 2000. B. LeRoy Davidson. Timber Press.

Lichens of North America. 2001. by Irwin Brodo, S.D. Sharnoff and S. Sharnoff. Yale University Press.

Mabberley’s Plant Book: A Portable Dictionary of Plants, Their Classification and Uses. 2008. David J. Mabberley. Cambridge University Press, New York, USA

Manual of Grasses for North America. 2007. edited by, Mary E. Barkworth, Laurel K. Anderson, Kathleen M. Capels, Sandy Long & Michael B. Piep. Utah State University Press.

Penstemons. 1999. Robert Nold. Timber Press.

Pitcher Plants of the Americas. 2006. Stewart McPherson. McDonald and Woodward Publishing Company.

Plant Identification Terminology: An Illustrated Glossary. 2nd ed. 2001. James G. harris and Melinda Woolf Harris. Spring Lake Pub.

Wild Orchids Across North America. 1998. Philip E. Keenan. Timber Press.