Sources Consulted
Also See: Opuntia Web References
A Dictionary of Botany, Little and Jones, Van Nostrand Reinhold Co, 1980, ISBN-13: 978-0442241698
Agaves of Continental North America, Howard Scott Gentry, 2004
Agaves, Yuccas, and Related Plants, a Gardener’s Guide, Irish and Irish, Timber Press, 2000
Biochemistry & Molecular Biology of Plants, Buchanan et al., 2002
Biodiversity Heritage Library, website
Botanicus, website
Cacti of Texas and Neighboring States, Weniger, University of Texas Press, second ed, 1988
Cacti of the Southwest, Weniger, 1970
Cacti of the Trans-Pecos and Adjacent Areas, Powell MA, Weedin JF, Texas Tech University Press, 2004 (last accessed January 6, 2015)
Cacti, Agaves, and Yuccas of California and Nevada, Ingram, Cachuma Press, 2008
Cacti, Biology and Uses, Nobel (ed), 2002, University of California Press
Cactiguide, website
Cactus and Succulent Digital Library, website (generous provider of The Cactaceae volumes)
Echinocereus, Special Issue, Quarterly Journal of the Cactus & Co. International Society, 1998
Gymnocalycium: A Collector’s Guide, Pilbeam and Balkema ,1995
Hardy Succulents, Kelaidis, GM, Storey Publishing, 2008
Highly Variable Chloroplast Markers for Evaluating Plant Phylogeny at Low Taxonomic Levels and for DNA Barcoding, Dong et al., 2012, online publication
Plant Speciation, Rieseberg and WIllis, 2007
PlantIllustrations.Org, website
Pricklypears commonly found in the United States and northern Mexico, Green with Ferguson, ISBN 10: 897987PP, 2011
The Cactaceae: descriptions and illustrations of plants of the cactus family, Britton and Rose, Carnegie Institution of Washington, v1 1919
The Cactaceae: descriptions and illustrations of plants of the cactus family, Britton and Rose, Carnegie Institution of Washington, v2 1920
The Cactaceae: descriptions and illustrations of plants of the cactus family, Britton and Rose, Carnegie Institution of Washington, v3 1922
The Cactaceae: descriptions and illustrations of plants of the cactus family, Britton and Rose, Carnegie Institution of Washington, v4 1923
The Cacti of the United States and Canada, Benson, Stanford University Press, 1982
The Cactus Conservation Institute, Inc, Online Library, website
The Cactus Family, Anderson, Timber Press, 2001
The Genus Echinocereus, Taylor, N, Timber Press and the Royal Botanic Gardens, Kew, 1985
The New Cactus Lexicon, Hunt (ed), 2006
The Plant List, website
The Role of Hybridization in Plant Speciation, Soltis and Soltis
The Sansevieria Book, Hermine Stover, 1983
The Succulent Plant Page, website
Trees, Shrubs & Cacti of South Texas, Everitt and Drawe, Texas Tech University Press,1993