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Malacothamnus nuttallii
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malvales
Family: Malvaceae
Subfamily: Malvoideae
Tribe: Malveae
Genus: Malacothamnus

Malacothamnus (bushmallow) is a genus of shrubs found throughout much of mainland California and on three of the Channel Islands. Outside of California, Malacothamnus is known from the northern half of Baja California and from a few disjunct locations in Arizona. Plants of this genus are most commonly found in early-successional, post-burn plant communities.[1] Malacothamnus are currently thought to be most closely related to the Iliamnas of the US interior and the Phymosias of Mexico, Central America, and the Caribbean.[2]


Taxonomy in the genus Malacothamnus has been controversial due to overlapping morphological variation and differences in opinion about how to treat that variation.[3][1] [4][5] [2][6] The controversy mostly arose from the many taxa included in the CNPS Rare Plant Ranking system that were not included in some treatments of the genus.[7] The most recent treatment used a combination of morphological and phylogenetic analyses to help clarify taxon boundaries and which taxa should be recognized, though some taxa still need further research. This treatment recognizes 21 species and 29 minimum-ranked taxa.[8][9][10][11][12][13]

Species included in the most recent treatment of the genus[13]


  1. ^ a b Kearney, T. H. 1951. “The Genus Malacothamnus, Greene (Malvaceae).” Leaflets of Western Botany VI (6):113–40.
  2. ^ a b Slotta, T. 2004. “Phylogenetics of the Malacothamnus Alliance (Malvaceae): Assessing the Role of Hybridization and Molecular and Morphological Variation in Species Delineation.” Ph.D. dissertation, Virginia Polytechnic Institute and State University.
  3. ^ Kearney, T. H. 1955. “Notes on Malvaceae VII: A New Variety in Malacothamnus.” Leaflets of Western Botany VII (12):289–90.
  4. ^ Bates, D. M. 1993. “Malacothamnus.” In The Jepson Manual: Higher Plants of California, edited by James C. Hickman, 751–754. Berkeley: University of California Press.
  5. ^ Bates, D. M. 2015. “Malacothamnus.” In Flora of North America North of Mexico, edited by Flora of North America Editorial Committee, 6:280–85. New York and Oxford.
  6. ^ Slotta, T. 2012. Malacothamnus. In B. Baldwin, D. Goldman, D. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken [eds.], The Jepson Manual: Vascular Plants of California, 884–885. University of California Press.
  7. ^ "CNPS Inventory of Rare and Endangered Plants: Malacothamnus"
  8. ^ Morse, K. "Malacothamnus - The Bushmallows"
  9. ^ Morse, K., and T. Chester. 2019. Malacothamnus enigmaticus (Malvaceae), a new rare species from the desert edge of the Peninsular Range in San Diego County, CA. Madroño 66: 103–119.
  10. ^ Morse, K. 2021. A morphological assessment of the Malacothamnus palmeri complex (Malvaceae). Crossosoma 44: 1–27.
  11. ^ Morse, K. 2023. Malacothamnus Volume 1: A Morphological Assessment of Taxonomic Boundaries in the Genus Malacothamnus (Malvaceae).
  12. ^ Morse, K. 2023. Malacothamnus Volume 2: A Phylogenetic Assessment of Taxonomic Boundaries in the Genus Malacothamnus (Malvaceae).
  13. ^ a b Morse, K. 2023. Malacothamnus Volume 3: A Revised Treatment of the Genus Malacothamnus (Malvaceae) Based on Morphological and Phylogenetic Evidence.

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