Utah Native Plant Society

The posts contained herein are intended to be informational, and any opinions expressed are mine alone.




Saturday, April 22, 2023

Stone's draba finally officially recognized as new to science

A plant species previously named in 1941 in honor of the late Dr. Bassett Maguire (botany professor at herbarium curator at Utah State University in Logan, Utah from 1931 until 1942 and then a curator and scientist at the New York Botanic Garden until his death in 1991) now once again is being recognized as having two infraspecific taxa based on recently published genetic studies (March 2023).

Plant species aren't necessarily named for the first person to make a plant collection of that ultimately named species.  But in this case, Dr. Maguire along with Dean Hobson and Ralph Gierisch on June 2, 1936 made a high elevation collection in Cache County in the Bear River Range that they knew was a species of Draba in the mustard family, but without identification of the species within that genus:


Maguire 13687 deposited at the Gray Herbarium (Harvard University) subsp. maguirei

The genus Draba is sometimes referred to as "Whitlow grass" and other related variations but it is not a grass species.

In 1941, C.L. Hitchcock named this plant as a new species, Draba maguirei, with two intraspecific varieties: var. maguirei and var. burkei.

On July 7, 1995, Doug Stone with Frank "Buddy" Smith made a collection of a plant in the Monte Cristo Range similar to D. maguirei at an elevation that was 1800 feet lower then the 1936 collection and brought it to the attention of mustard expert Dr. Michael Windham:


Stone 1804 of subsp. stonei (note the premature var. designation and author names)

Windham collected it in 1997:


Windham 97-118 subsp. stonei (note the premature var. designation and author names)

This same plant, as it turns outs, was collected by the USU's Dr. Richard Shaw in June of 1983.

Shaw 3132 subsp. stonei (with a handwritten premature var. designation and author names)


Since var. stonei was never published (until published as subsp. stonei in March of 2023), the annotations of the name to the specimens above was premature; it was based on the same understanding of research that had already been largely conducted in the late 1990's, and sometimes specimen sheets make reference to unpublished or expected names.  But, often there never is a publication of that name.  The naming of a species however requires a publication that meets the minimum threshold requirements of the ICBN (International Code of Botanical Nomenclature).  Just writing a proposed name on a herbarium specimen sheet (or "voucher") does not constitute a publication.

In May of 1999, USU's Dr. Mary Barkworth collected this later named taxon in Logan Canyon:

Barkworth 99.010 subsp. stonei at NYBG

Botanists Duane Atwood and Joel Tuhy separately also collected this same lower elevation plant in the 1980's before being described now as Draba maguirei C.L. Hitchc. subsp. stonei Windham via the recent publication.  Until now, those plants (as well as those referenced above) have simply been classified as Draba maguirei var. maguirei.

Based on chromosome counts and analysis provided in a 2004 paper , Windham and Beilstein moved Draba burkei, previously named as a variety of D. maguirei, to the species level. 

Oldest Draba burkei collection (May 1932, Box Elder Co.) by Melvin Burke (holotype)

It was thought that an analysis of plants still considered to be D. maguirei other than "burkei" was going to be made by 2005 based on initial conferences that I participated in relating to the Utah Rare Plant Guide (URPG) project.  Preparations were being made going back as far 2003 to add "var." stonei to the URPG (with the same author assumptions, i.e. by Windham and Beilstein) but those efforts then were paused awaiting a future publication, which in 2023 has now finally happened.  

Link to the publication: https://pubmed.ncbi.nlm.nih.gov/36779544/Full PDF.  Citation:

Windham MD, Picard KT, Pryer KM. 2023. An in-depth investigation of cryptic taxonomic diversity in the rare endemic mustard Draba maguirei. American Journal of Botany e16138.

Related prior article:

https://www.jstor.org/stable/41425341

The taxa in this complex have different ploidy levels:

Draba maguirei subsp. maguirei n=16

Draba maguirei subsp. stonei n=8

Draba burkei  (syn. D. maguirei var. burkei) n=10

All three taxa are northern Utah endemics.  Their ranges however do not overlap.   D. burkei occus in Box Elder, Cache, Morgan (barely) and Weber Cos.   The D. maguirei subspecies only occur in Cache County with subsp. stonei occurring somewhat to the south at lower elevations than subsp. maguirei

All three have yellow flowers with oblong leaves in basal rosettes.  The flowering stems are scapose (i.e. lacking leaves).  D. maguirei plants have longer leaves than D. burkei. There are differences in leaf and fruit trichomes (hairs).   D. burkei only has trichomes along its leaf margins.  This tends to be true also with subsp. maguirei whereas subsp. stonei has trichomes on blade surfaces.   Unlike the short-stalked and usually four-rayed trichomes of subsp. maguirei, subsp.stonei mostly has 2-rayed (bifurcate) trichomes; D. burkei has unbranched trichomes. 

Draba maguirei subsp. stonei (Teresa Prendusi, May 23, 2004, Logan Canyon, Utah)

Draba maguirei subsp. stonei leaves (Teresa Prendusi, May 2004, Logan Canyon, Utah)

D. maguirei and D. burkei are both on the Forest Service's (Intermountain Region, R4) sensitive species list that has not been updated since 2010.  Both currently have G2 (Imperiled) NatureServe rankings.  They have been included in Utah Native Plant Society rare plant lists since at least 2003 on-line and have been ranked with a conservation priority of "Watch" (third highest).  These now newly recognized subspecies have not yet been ranked and their conservation priority could end up being now higher when ultimately re-reviewed.  D. maguirei was also included in the 1991 Utah Endangered, Threatened and Sensitive Plant Field Guide, so has been on the radar for a long time.

The URPG has accordingly been updated.  Utah rare plant guide links to each of these three taxa follow:

https://www.utahrareplants.org/pdf/Draba_burkei.pdf

https://www.utahrareplants.org/pdf/Draba_maguirei_subsp_maguirei.pdf

https://www.utahrareplants.org/pdf/Draba_maguirei_subsp_stonei.pdf

Supplemental page to the above:

https://www.utahrareplants.org/pdf/Draba_maguirei_subsp_stonei_supp.pdf


Note: it is coincidental that the plants in this complex have all been named for individuals* that have a last letter of "e" in their names, i.e.:  Maguire, Burke, and Stone.  These individuals were all males so hence the "i" ending in the corresponding scientific names.  

*Purely opinion: I am not a big fan of naming plants or animals after people.  A better approach is to, whenever possible, try to use either a characteristic of the plant or something that relates to where it occurs (i.e. geographic location or habitat type for example) or something else related to its biology in forming the specific or varietal epithet.  Admittedly this can also be problematic since that distinguishing character or location may end up being different than originally thought, leading to misleading names.  And that is made harder with cryptic taxa like those discussed here. Nonetheless, these are biological organisms that came into existence over a likely vast evolutionary time period, and were also known by others long before they were ever named. They deserve appropriate respect.  It is nice to honor someone who may have made a huge botanical contribution or even with simply an incidental discovery of some kind, but that person's name could just as easily be used as part of the common name (for which there are no rules when it comes to plants) if applicable, or indicated in the published write-up for the taxon.  To have a word that translates to something with respect to the plant itself is I think far more meaningful.  Naming plants after your spouse, your children, your grandchildren, your friends or colleagues, etc. (or even the person who either first recognized something as undescribed, or who collected it first even though those circumstances make more sense), to me borders on being something that is more typically inappropriate for a scientific endeavor (and despite the precedent that has been set in doing so, the one frowned upon approach is not to name something for yourself - the line is at least drawn there!).  Yet, and with all due respect, the scientific names of our native plant species are quite literally littered with the often rather meaningless names of people.