APG III and IV include this family into an expanded Asparagaceae in a branch with Hyacinthaceae by placing most taxa into the subfamily Brodiaeoideae. The type genus, Themis, had only a single species published in 1866, Themis ixioides, considered an invalid name. It is now one of the many synonyms for Triteleia ixioides. In 2021 the Jepson eFlora, which contains taxonomic treatments and identification keys for native and naturalized plants occurring in California continues to include Androstephium, Bloomeria, Brodiaea, Dichelostemma, Dipterostemon, Muilla, and Triteleia in Themidaceae.
The process of reaching this agreement was a rather complicated affair:
All the former cormous genera that were once considered to belong in the Liliaceae family from Mexico and Western North America were speculated as belonging to Themidaceae at the beginning of the 21st century, although some taxonomists suggested moving them back or placing them in the morphologically similar Alliaceae (now part of Amaryllidaceae). In 2021 the Flora of North America still has them listed in the Liliaceae family. A 2002 phylogenetic evaluation concluded that Themidaceae is a monophyletic family that is sister to Hyacinthaceae within Asparagales. (See A Phylogenetic Evaluation of a Biosystematic Framework: Brodiaea and Related Petaloid Monocots (Themidaceae), J. Chris Pires and Kenneth J. Sytsma, American Journal of Botany 89(8): 1342-1359, 2002. https://bsapubs.onlinelibrary.wiley.com/doi/full/10.3732/ajb.89.8.1342)
|Genera of Themidaceae|
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