San Diego State University
Department of Biology



MICHAEL G. SIMPSON, Professor Emeritus

Curator, SDSU Herbarium

Research Gate Profile







Mailing Address

Dr. Michael G. Simpson
Department of Biology
San Diego State University
San Diego, CA 92182-4614

B.S. : University of Florida
M.S. : University of North Carolina, Chapel Hill
Ph.D. : Duke University

General Research Interests: 
Plant systematics, plant taxonomy, floristics.

My research in plant systematics lab focuses on the systematics and evolution of land plants with three general objectives:
   1) to infer the phylogenetic relationships of plant groups and to use that pattern of evolutionary history to assess aspects of character evolution, biogeography, ecology, and evolutionary process;
   2) to investigate the delimitation of plant species and infraspecies, especially in evaluating rare/endangered taxa;
   3) to discover the plant species and community structure of regions in floristic studies.

I have interests in American amphitropical disjunct (AAD) plants, those that occur in North and South America, on either side of the neotropics.
See our American Amphitropical Disjunction Working Group:
   Figshare site:
   Figshare data (a compendium of AAD vascular plants):
   SDSU website listing examples, links, and resources:

My field work in Chile and Argentina was supported in part by the National Geographic Society. I and my colleagues are working on the phylogenetic relationships of the Amsinckiinae (Boraginaceae), many of which have an American amphitropical disjunct plants. See my web page on
Some Plants of Chile/Algunas Plantas de Chile.



1-4 October 2018
   I and many others of the NSF supported Digitization TNC attended the iDigBio Summit in Gainesville, Florida. The summit was very informative and inspring. iDigBio has many resources, for research and teaching.

10 September 2018
   I was honored to be a part of this, a new species of the genus Antiphytum, A. geoffreyi, Boraginaceae, described by Nidia Mendoza-Díaz of UNAM, Mexico City. This is in a subfamily (Echiochiloideae) I don't study, but helped to realize what it was when discovered by George Hinton, one of a family (I think three generations) of plant collectors in central Mexico. There was already an Antiphytum hintoniorum. This new one was named after George's son, Geoffrey. This new species is a bit of a missing link in the subfamily. (pdf)

11 June 2018
   Good news! We received funding for our NSF grant, entitled "Digitization TCN: Collaborative Research: Capturing California's Flowers: Using digital images to investigate phenological change in a biodiversity hotspot. The SDSU Herbarium is a small part of this grant (we have about 22,000 specimens). We will be digitizing and imaging the specimens of our entire collection over the next year or two. See links at the SDSU Herbarium website.

27 April 2018
   Makenzie Mabry's article on the genus Cryptantha came out in the journal Systematic Botany. This was the product of her M.S. thesis at San Diego State.  Congratulations, Makenzie! See: Mabry, M. E. and M. G. Simpson. 2018. Evaluating the monophyly and biogeography of Cryptantha (Boraginaceae). Systematic Botany 43: 53-76. (pdf)

22 December 2017
   Our article on the phylogeny of the intriguing "popcorn flowers" came out in the journal Taxon. This was the joint effort of my four outstanding (former) graduate students: Kristen, Lee, Makenzie, and Matt. See: Simpson, M. G., C. M. Guilliams*, K. E. Hasenstab-Lehman*, M. E. Mabry*, and L. Ripma*. 2017. Phylogeny of the popcorn flowers: Use of genome skimming to evaluate monophyly and interrelationships in subtribe Amsinckiinae (Boraginaceae). Taxon 66: 1406–1420. (pdf)

27 November 2017
   After many months, and a lot(!) of work, our articles on American amphitropical disjunct (AAD) plants came out in the American Journal of Botany (see and my Publications). Matt Guilliams, Leigh Johnson, and I were co-editors on this special issue, with an introductory paper and 12 research articles by experts in the field. A good effort. And, we established an AAD Working Group <> on figshare, with an associated dataset that we will update periodically. The latter is a means of keeping research data current, which we hope will serve as a model for other scientists.

20 July 2017
   Nuri Benet-Pierce, a Research Associate at SDSU, and I just published a paper on Chenopodium. Nuri put a lot of hard work into this paper (and is already working on another one): Benet-Pierce, N., and M. G. Simpson. 2017. Taxonomic recovery of the species in the Chenopodium neomexicanum complex and description of Chenopodium sonorense sp. nov. Journal of the Torrey Botanical Society 144: 339-356. (pdf)

11 May 2017

   Attended a field trip led by Drs. David Keil, Matt Ritter, and Jenn Yost (and local botanist "Doc"; group picture), along the Rocky Butte Truck Trail, near Pine Mountain, in the Santa Lucia Mountain range of San Luis Obispo County.

10 May 2017

   I gave a talk for the Plant Science Club at Cal Poly San Luis Obispo, entitled "Traveling in Chile to Assess the Evolutionary and Biogeographic History of the Popcorn Flowers". It was great to meet the students, who asked very insightful questions.

18-20 April 2017
   I was fortunate to go along on field escursions to Baja California, with Margie Mulligan, Jon Rebman, and Sula Vanderplank. We traveled somewhat south of San Quentín, including Valle Tranquilo and some surrounding estuaries and dunes. With a little help from us, Jon added 40 new records to this region. Jon and I also collected a large-leaved Cryptantha in tall sand dunes, a plant that we had recognized earlier from specimens to likely be a new species. We will be describing this, hopefully in the next year.

24-26 March 2017

   I led an event for the 2017 Jepson Workshop Series, entitled "Introduction to Desert Plant Families" at the
   Steele/Burnand Anza Borrego Desert Research Center in Borrego Springs.

21 February 2017

   I gave a talk at the San Diego Natural History Museum, entitled "The Astounding Diversity of Sex in Plants",
   part of a symposium of talks on sex in mammals, frogs, birds, insects, and plants (pdf)

9 February 2017
   Ron Kelley and I just published a new (replacement) name for a Cryptantha, calling it Cryptantha juniperensis. (pdf)

21 January-6 May 2017
Co-teaching our Saturday Field Botany of San Diego County with some great botanists:
     Scott McMillan, Margie Mulligan, Tom Oberbauer, Jon Rebman, and Sula Vanderplank

9 January 2017
I gave a talk at the Anza Borrego Desert State Park Botany Society: Assessing Biodiversity: Collections and DNA

9 January 2017
Layla Aerne-Hains and I published a paper on the anatomy of the Haemodoraceae!
   Aerne-Hains, L. and M. G. Simpson. 2017. Vegetative anatomy of the Haemodoraceae and its phylogenetic significance. International Journal of Plant Sciences 178: 117–156.
   Layla put a lot of hard work into this. Congratulations, Layla!

14-27 December 2016
   Articles on naming of Dudleya hendrixii:
   L. A. Times
San Diego State University

   San Diego Union Tribune

16 December 2016
Publication of: Dudleya hendrixii, A new, rare species from Colonet Mesa, Baja California
   Named after guitarist Jim Hendrix!
   McCabe, Dodero, and Simpson 2016, Madroño 63: 359-365.

19-21 December 2016
   I gave at talk at: Plant Diversity at the Huntington Botanical Gardens: Part Trois! (Biology 330)-Cactaceae
   Huntington Botanic Garden, Pasadena, California
   Instructors: Dr. Matt Ritter, Dr. Jenn Yost (Cal Poly, San Luis Obispo)
   Speakers: Dr. Michael Simpon - Phylogenetic relationships in the Cactaceae; Dr. Jim Mauseth - Cactus diversity, morphology, and taxonomy;   
   Dr. Jon Rebman - The Opuntioideae, cactus discovery and collection; Ernesto Sandoval - Cacti in horticulture

7 October 2016
I gave a talk at Rancho Santa Ana Botanic Garden: Seminars in Systematic & Evolutionary Biology, Claremont, California
   Simpson, M. G. Phylogeny, Biogeography, and Character Evolution of the Popcorn Flowers: A Model System of American Amphitropical Disjunct Plants

1-2 September 2016

I gave a talk at the III International Boraginales Meeting, Nees Institute for Plant Biodiversity, Bonn, Germany
   Simpson, M. G. The status of Cryptantha: Taxonomy, phylogeny, and biogeography

2 August 2016
I co-lead a colloquium: Botany 2016, Savannah, Georgia. Colloquium: Patterns and Processes of American Amphitropic Disjunct Plants: New Insights
      Simpson, M. G., and M. C. Guilliams. What are American amphitropical disjunctions and why are they interesting
Guilliams, C. M., Mabry, M., Hasenstab-Lehman, K., Baldwin, B. G., Simpson, M. G. Exploring patterns and mechanisms of American amphitropical disjunction in the Amsinckiinae (Boraginaceae).

28 June 2016
   I gave a talk to the Mensa Foundation, colloquium on "Flora, Fauna, and the Future":
   "Phylogeny, Biogeography, and Character Evolution of the Popcorn Flowers, a Model System of American Amphitropic Disjunct Plants."
   Town and Country Resort and Convention Center, San Diego, California.

May 2016
Check out the video clip on SDSU Botany! and the SDSU Herbarium

Plant Systematics Resources
SDSU Herbarium

Courses Taught at SDSU in the past
Principles of Organismal Biology (Biology 204)
Economic Botany (Biology 460)
Plant Systematics (Biology 530)
Taxonomy of California Plants (Biology 531)