All illustrations are by Winnifred S. Casacop, with the exception of illustrations 1, 2, 3, 4, 5, and 6, which are by Arthur Mount.
M. Amaranthus, Mycorrhizal Applications, photos 1, 2, 3, 4, 5, 6, 7 (courtesy Jim Deacon, University of Edinburgh), 8, 9, 10, 11 (courtesy Eddie Loy, Star Seed), 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and 22.
Lynn Betts, USDA-NRCS, photo 1.
Efren Cazares, MycoRoots, photos 1 and 2.
Michelle M. Cram, USFS, photo 1.
Nigel Davenport, The Nutrient Company, photo 1.
Patricia D. Duncan, Environmental Protection Agency, photo 1 (courtesy National Archives).
Kristine Nichols, USDA-ARS, photo 1.
Charles O’Rear, photo 1 (courtesy Special Media Archives Services Division, NWCS-S).
USDA-ARS, photo 1.
USFS, Northeastern Area Archive, photo 1.
Used under a Creative Commons Attribution 3.0 license
Robert L. Anderson, USFS, photo 1.
Joseph O’Brien, USFS, photo 1.
Used under a Creative Commons Attribution–Noncommercial 3.0 license
J. H. O’Bannon, photo 1.
Used under a Creative Commons Attribution 2.0 Generic license
SuSanA Secretariat, photo 1.
Used under a Creative Commons Attribution–Share Alike 4.0 International license
Rowan Adams, photo 1.
Mylène Durant, photo 1.
Used under a Creative Commons Attribution–Share Alike 3.0
Unported license
BMK Wikimedia, photo 1.
Roland Gromes, photo 1 (right).
André-Ph.D. Picard, photo 1.
Silk666, photo 1.
Used under a Creative Commons Attribution 3.0 Unported license
Forest and Kim Starr, hear.org/starr, photo 1.
Used under GFDL and Creative Commons Attribution 3.0 Unported licenses
Mike Guether, photo 1.
Used under a Creative Commons Attribution–Share Alike 2.5 license
John Womack, photo 1.
Used under a Creative Commons Attribution–Share Alike 2.5 Generic license
Bernd Haynold, photo 1.
Used under a Creative Commons Attribution–2.5 Generic license
David P. Hughes (left), Maj-Britt Pontoppidan (right), photo 1.
Used under a Creative Commons Attribution–2.0 Generic license
U.S. Fish and Wildlife Service Southeast Region, photo 1.
Used under a Creative Commons Attribution–Share Alike 2.0
Germany license
Jörg Hempel, photo 1.
Released into the Public Domain
George Chernilevsky, photo 1.
Masur, photo 1 (left).
Jonson 22, photo 1.