Angiosperm Phylogeny Phylogenetic trees, technical descriptions of all orders and families, references, and links. By Peter Stevens of the Missouri Botanical Garden. http://www.mobot.org/MOBOT/Research/APweb/
Flowering Plant Gateway Various paths for exploration or comparison of four major flowering plant classification systems (Cronquist, Takhtajan, Thorne and the Angiosperm Phylogeny Group system). From Texas A&M University. http://www.csdl.tamu.edu/FLORA/newgate/cronang.htm
The Families of Flowering Plants A taxonomical database with descriptions and illustrations of each family, and an interactive key to families. http://delta-intkey.com/angio/
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