These are print and online references that we have used to help identify plants we've photographed in our travels outside California.
Flora of North America.
http://www.efloras.org/ The online and multi-volume print set are also very useful for California natives.
Tropicos (Missouri Botanical Garden)
ITIS http://www.itis.gov/ ITIS (Integrated Taxonomic Information System) has taxonomic information on
plants, animals, fungi, and microbes of North America and the world. There are no photos associated with this site.
ITIS and Jepson do not always agree on the accepted scientific names of plants.
Native Plants Hawaii. http://nativeplants.hawaii.edu/
Starr Environmental Resources. http://www.starrenvironmental.com/resources/
Manual of the Flowering Plants of Hawai'i, Volumes 1 & 2; Wagner, W., Herbst, D., and Sohmer, S., 1999.
Hawaii Blossoms Hargreaves, Dorothy & Bob 1958
Hawaii: A Natural History; Carlquist, Sherwin, 1980.
Hawaiian Coastal Plants; Merlin, Mark, 1999.
Hawaiian Forest Plants; Merlin, Mark, 2005.
Hawaii's Ferns and Fern Allies; Palmer, Daniel, 2003.
Hawaii's Native Plants; Bohm, Bruce, 2004.
Hawaii's Trees and Shrubs (Pocket Guide); Pratt, H.,2006.
Minnesota Wildflowers. https://www.minnesotawildflowers.info/
New Mexico Flora. http://www.polyploid.net/swplants/
Flora Neomexicana Vol I:Annotated Checklist; Allred, Kelly, 2012.
Flora Neomexicana Vol II:Glossarium Nominum; Allred, Kelly, 2012.
Flora Neomexicana Vol IIIa:Field Keys;Allred, Kelly, 2012.
Wisflora: Wisconsin Vascular Plant Species. http://www.botany.wisc.edu/wisflora/
Cofrin Center for Biodiversity. http://www.uwgb.edu/biodiversity/resources/plants.asp
Wisconsin Flora; Chadde, Steve, 2013.
Wildflowers of Door County; Mahlberg and Mahlberg, 2000.
Wildflowers of Wisconsin; Tekiela, Stan, 2000.
Wildflowers of Wisconsin and the Great Lakes Region; Black, M. & Judziewicz, E., 2009.
Wildflowers of Wisconsin and the Upper Midwest; Black, M. & Judziewicz, E., 2008.
Michigan Flora, Volumes 1 (1972), 2 (1985) & 3 (1996). [Note: useful for Wisconsin before the 2013 Wisconsin Flora came out.]
The Flora of Baja California. http://bajaflora.org/
Baja California: Plant Field Guide; Rebman, Jon and Roberts, Norman, 2012.