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Xanthisma DC. was treated for most of its history as a single-species genus. Semple (1974) monographed the genus at this stage. Xanthisma was greatly expanded to include sect. Blepharodon, sect.Havardii and, sect. Sideranthus often included in the too broadly defined Haplopappus and Machaeranthera. In doing so, both North American species of Astereae with well-studied B-chromosomes were placed in a single genus: Xanthisma texanum and X. gracile (syn: Haplopappus gracilis; 2n=4, the lowest known chromosome number for a plant). The treatment here follows Hartman (2006 Flora North America).

Xanthisma sect. Xanthisma

• Xanthisma texanum DC.

Xanthisma sect. Blepharodon

• Xanthisma grindelioides (Nutt.) D.R. Morgan & R.L. Hartman
• Xanthisma coloradoense (A. Gray) D.R. Morgan & R.L. Hartman
• Xanthisma blephariphyllum (A. Gray) D.R. Morgan & R.L. Hartman
• Xanthisma gypsophilum (B. L. Turner) D.R. Morgan & R.L. Hartman

Xanthisma sect. Havardii

• Xanthisma viscidum (Woot. & Standl.) D.R. Morgan & R.L. Hartman

Xanthisma sect. Sideranthus

• Xanthisma gracile (Nutt.) D.R. Morgan & R.L. Hartman
• Xanthisma junceum (Greene) D.R. Morgan & R.L. Hartman
• Xanthisma spinulosum (Pursh) D.R. Morgan & R.L. Hartman

Last revised 5 May 2025 by J.C. Semple

© 2025 J.C. Semple, including all photographs unless otherwise indicated