Keir Morse - Botanist & Photographer

Malacothamnus -The Bush-mallows

Malacothamnus jonesii

For my PhD dissertation at Rancho Santa Ana Botanic Garden, I'm studying the genus Malacothamnus (Malvaceae) which has several conflicting taxonomic treatments and many rare taxa. I am using a combination of morphometric analyses, Restriction site Associated DNA Sequencing (RAD-Seq), comparative phenology, and extensive field evaluations to resolve the taxonomy of the genus Malacothamnus and evaluate the conservation status of each taxon. This work will hopefully be completed by 2022. I hope to fill in this web page with more resources on the genus as I have time.

iNaturalist Project

I've created an iNaturalist project to help with this research which you can visit here. iNaturalist users have been a great help in documenting locations, variation, and phenology in the genus Malacothamnus. All observations are welcome. If you want help identifying Malacothamnus, this is a good place to post your observations as I regularly check this site. Tips on what to photograph for a good ID are here. If you post Malacothamnus observations on iNaturalist, follow these instructions to share your coordinates with the project to make your observations much more useful.

While I'm putting very little time into it, a secondary iNaturalist project looking at the animals found interacting with Malacothamnus is here. Observations for this project are welcome as well.

Treatments and Identification

As mentioned above, there are several conflicting treatments. They are all problematic one way or another mostly due to lumping, splitting, and a lot of overlapping morphological characters. Treatments follow below. If you want help with identification beyond the treatments, see the iNaturalist Project section above. Calphotos is also useful to check IDs, but some photo IDs could be questionable.

I'm mostly following the Kearney treatment at present until I can resolve the taxonomic questions and produce something better. Kearney was more of a splitter, but this treatment still actually lumped several taxa from previous treatments. This treatment seems to follow the current evidence the most closely and includes rare taxa lumped by other treatments. The keys aren't perfect, but better than nothing. The Munz treatment mostly follows Kearney and is a bit simplified, so this is another good option. These treatments are missing both Malacothamnus palmeri var. lucianus and Malacothamnus enigmaticus. The Munz treatment is missing taxa from Mexico.

Do not use the Flora of North America or Jepson treatments. The 1993 Jepson Manual and Flora of North America treatments by David Bates are pretty much identical to each other. The taxa in these treatments were way over-lumped making them very problematic in relation to rare taxa. To the author's credit, he does say that the Kearney treatment is as justifiable as his. Likewise, the current Jepson Manual treatment is best avoided. Author Tracey Slotta made some good progress in splitting back out some lumped taxa based on morphological analyses, but her key is also problematic in various ways.

Draft regional keys and guides:
- Key to the Malacothamnus of Los Angeles, San Bernardino, and Kern Counties, CA
- Key to the Malacothamnus of Monterey and San Luis Obispo Counties, CA
- Key to the Malacothamnus of the Sierra Nevada Range, CA
- Illustrated guide and key to the Malacothamnus of San Diego, Orange, and Riverside Counties, CA
- Illustrated guide to distinguishing Malacothamnus from Sphaeralcea

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