Malvaceae Addendum 1

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Malvaceae Addendum
Latest Update W.P. Armstrong, 2 October 2021
Lavatera Species Now Placed In The Genus Malva
  Links To More Malvaceae Images On Other Wayne's Word Pages  
When I taught Plant Identification (Botany 110) at Palomar College on Thursday nights during spring semesters of previous mellennium, I emphasized naturalized weeds in my "keying out" labs. Depending on spring rains, they were plentiful and I didn't feel bad about pulling up masses of them for my classes. In addition, students very familiar with cultivated plants usually could not recognize the species name and were forced to use the taxonomic keys with extensive botanical terminology. In fact, my textbook was the Flora of San Diego County by Mitchel Beauchamp with keys based on the Flora of California and Flora of Southern California by P.A. Munz. When these books were out of print I used The Jepson Manual which was quite challenging. I must say that using taxonomic keys in the lab was an outstanding teaching method that introduced students to plant taxonomy. Rather than rote memorization, students learned the skill of using dichotomous keys that work the same in floras throughout the world, providing you can read the language. On some nights, students were so engrossed with their unknowns that they didn't want to leave the lab, even after 10:00 PM when the parking lots were empty!

Computer generated phylogenetic trees (cladograms) based on DNA sequencing have resulted in drastic changes to many plant families. Modern cladograms of animal and plant groupings show all taxa descending from a common ancestor. For this reason, the nomenclature in modern floras, such as The Jepson Manual, are very different from previous floras. This is especially true of the mallow family (Malvaceae), which now contains trees and shrubs of the chocolate family (Sterculiaceae: Cacao & cola nut), the basswood family (Tiliaceae: Basswood & jute), and the bombax family (Bombacaceae: Kapok, floss silk tree & balsa). The Malvaceae contains some of the most beautiful wildflowers and cultivated trees & shrubs in San Diego County, and some economically important species. No where is this more apparent than on the beautiful Palomar College campus.

Since I wrote the duckweed section for Jepson Manual I am very familiar with phylogenetic trees and how plant families can change with new DNA analysis. In fact, I lost my entire duckweed family (Lemnaceae) because all the genera and species were moved into the subfamily Lemnoideae within the arum family (Araceae). In general appearance, duckweeds look nothing like Philodendron and Dieffenbachia, however, their DNA indicates a close affinity.

  Wayne's Word Treatment Of The Subfamily Lemnoideae  
It was difficult to explain these complex phylogenetic (cladistic) topics when I taught my on-line classes early in the 21st century (3rd millennium). Sometimes I would resort to meeting my students in a vacant classroom on campus! For your enjoyment, the following link shows the placement of 5 duckweed genera within the arum family cladogram. You may need to zoom in (+) on the cladogram pdf. Although Pistia (water lettuce) looks a little like a giant duckweed, they are actually far apart in the cladogram.

  My 5 Duckweed Genera Are Now In Arum Family Cladogram!  
DNA Terminology & Monophyletic Taxonomic Groupings
A More Detailed Summary Of Monophyletic Groupings

Back To The Mallow Family (Malvaceae)
On Friday 2 October 2021, I photographed the beautiful Mediterranean bush mallow (Lavatera maritima) in full bloom near the Palomar College Science Building. We also have a California species native to the Channel Islands (L. assurgentiflora). The latter species is also naturalized along coastal bluffs of California. As you will see in the following image, both shrubs are now placed in the genus Malva along with our California naturalized weedy species of Malva! In addition to extensive DNA analysis, some species have been named multiple times by different authors during the past two centuries. It is an enormous task sorting through all the published synonyms to determine the valid, scientific binomial for each species.

1. Plants of the World Online
2. International Plant Names Index (IPNI)
3. The Kew Plant List
4. Flora of North America
5. Consortium of California Herbaria (CCH1)
6. Data From the California Phenology (CCH2)
7. Jepson Herbarium, University of CA Berkeley
8. Global Biodiversity Information Facility (GBIF)
9. Flora Iberica (Iberian Peninsula of SW Europe)
There are many on-line resources for the correct, valid scientific binomials of plants. There are also many published monographs for specific genera available on the Internet or through interlibrary loan. Sometimes even these scholarly references don't always agree with each other.

Mediterranean bush mallow (Malva subovata), syn. Lavatera maritima.


Two Additional Attractive Species Grown From Seed

Wild (naturalized) Malva pseudolavatera from Vista & Twin Oaks Valley.

Malva sylvestris grown from seed. The flowers are similar to M. pseudolavatera, but are generally larger and in more showy, dense clusters. Naturalized populations identified as this species in San Diego County are actually M. pseudolavatera.

Several years ago I discovered a prostrate (mat-forming), annual Malva in a vacant field west of Palomar College (near CVS pharmacy). Its growth form was completely different from other naturalized, weedy Malva species reported for San Diego County. I thought perhaps it might be an unreported species for the county or possibly for the state. I sent herbarium specimens to several Malvaceae authorities at botanical gardens in Phoenix, San Luis Obispo, Santa Barbara, and Cambridge University, England. Former student, Steven Disparti, grew this species at his home in Escondido, along with other Malva species for comparison. We named the plant "Malva X" and spent hundreds of hours investigating this unusual mallow. Our work is summarized at the following link.

  Unusual Naturalized Malva In San Marcos  

Malva X grown from seed clearly retained the decumbent growth form. The plants are vigorous, prolific seed-producers. 13 July 2012

Flowers of Malva X are similar to M. pseudolavatera except they are smaller and lighter in color.
The proper scientific names for naturalized and cultivated species in the Malvaceae have challenged some taxonomists for centuries. I must say that during my investigations of the weedy, naturalized Malva species in California and Arizona, I became quite fascinated with this genus. Even the small flowers of weedy species like cheeseweed (Malva parviflora) have attractive flowers.

Field of Malva parviflora in Twin Oaks Valley during the wet spring of 2010.

  Cooked Greens Of Malva parviflora  

Close-up view of Malva parviflora in Twin Oaks Valley. The flower is 6 mm across.

California Native Wildflowers in the Malvaceae: Left: Bush Mallow (Malacothamnus fasciculatus) in Palomar College Arboretum. Center: Apricot mallow (Sphaeralcea ambigua var. ambigua). Right: Desert 5-Spot (Eremalche rotundifolia).

Mexican bush mallow (Phymosia umbellata) on Palomar College campus.
Links To More Images Of Malvaceae On Wayne's Word:

  Palomar College Botanical Garden Mallow Family Page   
  Herbaceous & Shrubby Malvaceae:  
See Beach Hibiscus: A Textile Plant
A Flower Of Another Beach Hibiscus
See The Seed Capsule (Boll) Of Cotton
   Unusual Naturalized Malva In San Marcos
   

  Campus Trees In Malvaceae:  
Tiliaceae: Tilia & Sparmannia
  Bombacaceae: Floss Silk Tree  
Sterculiaceae: Brachychiton
Cow Itch Tree (Lagunaria)
  More Fascinating Trees In Malvaceae:  
Unusual Pods & Putrid Flowers Of Indian Almond
  Trees With Remarkable Fruits, Including Ocean Drifter