Thursday, June 7, 2018

Botanical Perplexity in the Southern Utah Desert

The bush on the left isn’t dead.
On the Waterfall Trail behind the San Rafael Reef, west of Arches National Park, I came across an unfamiliar shrub. From a distance it looked dead, but up close I saw small green oval leaves with serrated upper margins, and fruit that looked like tiny immature apples. These suggested serviceberry, the genus Amelanchier, and I felt that pleasing cognitive dissonance that comes when something is both familiar and strange. I looked forward to solving the mystery, putting a name on this shrub.
The small glabrous (not hairy) leaves were problematic.
Developing fruit, with anthers and styles still visible.
Serrated leaves and pomes of Amelanchier (Juneberry, Serviceberry); source.

This was supposed to be a short post—put together quickly, just a few photos and some information about the serviceberry, finishing with a sunset. But identification proved elusive, in part due to the small glabrous (hairless) leaves that didn't fit any Utah species, but mainly because of the legacy of struggling Amelanchier taxonomists.

The overlapping and highly variable “species” of this genus confound even the experts. In 1946, eminent botanist Merritt Lyndon Fernald went so far as to claim that no other genus in North America, except perhaps Rubus and Crataegus (raspberries and hawthornes), offered as much “perplexity” as Amelanchier (1).

The serviceberry I saw along the Waterfall Trail is a case in point. For a century botanists have debated its status, moving it from species to subspecies to synonym and most recently back to species. Not surprisingly, my path through the literature was tortuous. But I did meet some interesting characters, starting with Ivar Frederick Tidestrom.
I.F. Tidestrom, photo courtesy USGS.
Ivar Tidestrom ran away from home in Sweden in 1880, and headed for the United States. He served in the US Army (cavalry), enrolled in the University of California as an engineering student, and soon switched to botany. In 1919 while collecting plants in the Charleston Mountains northwest of Las Vegas, Nevada, he found an unfamiliar serviceberry with small glabrous leaves in the “piñon belt near Wilson’s ranch”. Four years later, he published it as a new species: Amelanchier nitens.
Amelanchier nitens, collected by Ivar Tidestrom on May 27, 1919; US National Herbarium.

In the late 1930s, Ira Waddell Clokey, a mining engineer and botanist, was finishing up his intensive study of plants of the same Charleston Mountains. He went to Tidestrom’s site to collect more material of Amelanchier nitens. He concluded it didn’t warrant full species status. Instead, he called it Amelanchier utahensis ssp. covillei (Clokey 1945).
Ira Clokey died in 1950, just after his Flora of the Charleston Mountains was accepted for publication (source).

Around the same time, G. Neville Jones took on a revision of North American Amelanchier, published in 1946. He described Tidestrom’s serviceberry from the Charleston Mountains as an “extreme form” that “intergraded completely with the typical pubescent [hairy] forms” of Amelanchier utahensis, a widespread and highly variable species (2). Thus Amelanchier nitens was reduced to synonymy, becoming part of Utah Serviceberry, where it remained for almost 60 years.

The latest revision of Amelanchier was done by Christopher Campbell and five colleagues, for the Flora of North America (2015 online). In it, I found a species description that matched the serviceberries along the Waterfall Trail pretty well—Amelanchier nitens! So we’ve come full circle. Tidestrom’s serviceberry has been resurrected as a species, now with a common name—Shining Shadbush (shining for the glabrous leaves; shadbush is one of many common names for Amelanchier).
Does Shining Shadbush grow in the “piñon belt” of Utah?

Did I finally have a name for my mystery shrub? Maybe. Unfortunately, Shining Shadbush is said to grow only in the Charleston Mountains in Nevada and in a limited area near Sedona, Arizona, i.e., not in Utah. But then I read the fine print (emphasis added):
“The authors have observed incomplete herbarium specimens conforming to Amelanchier nitens morphology from Colorado, New Mexico, and Utah.”
So the serviceberries along the Waterfall Trail may be the Shining Shadbush, Amelanchier nitens. But given the “perplexities” of serviceberry classification, it’s probably best not to worry about a name. Instead, just enjoy Amelanchier’s approach to biodiversity!

Thus ends my winding tale ... except for the sunset. Here’s one looking south from the Waterfall Trail.
West side of San Rafael Reef, Henry Mountains in distance.

Notes

(1) In the Introduction to his American Species of AmelanchierG. Neville Jones (1946) summarized the evolving struggle of taxonomists to classify serviceberries, with wild swings in numbers of species (emphasis added):
“The earlier students [19th century] of the North American flora, including Michaux, Pursh, Nuttall, Torrey, and Gray, took the view that [Amelanchier] in the western hemisphere consisted of only one, or at the most very few, highly variable species. … there now may be found in botanical literature nearly two hundred binomials and trinomials representing the species of Amelanchier in America.”
(2) Jones also described convincingly the challenge of serviceberry identification:
“Anyone who studies Amelanchier in the field, or who examines large series of specimens in herbaria, is at once struck by the extraordinary variation of the foliage that occurs even in the same species, as manifested in different stages of development and from various habitats. … When placed side by side, specimens of the same species in these different stages of development often show an almost incredible dissimilarity and have been not infrequently mistaken for different species.”

Sources

Most of these were accessed online via the Biodiversity Heritage Library. Their wonderful collection is newly enhanced with Full Text Search, more information here.

Campbell, CS, et al. 2015 (online). Amelanchier, Flora of North America vol 9. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=101333

Clokey, IW. 1945. Notes on the flora of the Charleston Mountains, Clark County, Nevada. Madroño 8:56-61. https://biodiversitylibrary.org/page/47877692

Clokey, IW. 1951. Flora of the Charleston Mountains, Clark County, Nevada. University of California Press (Amelanchier pp 119-120). https://books.google.com/books?id=GuBVI1nC-50C&source=gbs_navlinks_s

Jones, GN. 1946. American species of Amelanchier. Urbana: The University of Illinois Press (A. nitens pp 92-93). https://www.biodiversitylibrary.org/item/105913 

Tidestrom, IF. 1923. New or noteworthy species of plants from Utah and Nevada. Proceedings of the Biological Society of Washington 36:181-184. https://www.biodiversitylibrary.org/page/34510710#page/201/mode/1up

Tidestrom, IF. 1925. Flora of Utah and Nevada. Contributions from the United States National Museum 25 (Amelanchier nitens pp 282-284). https://catalog.hathitrust.org/Record/001494238


2 comments:

  1. Beautiful last image and fascinating information about western Serviceberries. We have several species here in Wisconsin, and increasingly people are planting them as they realize the appeal of these beautiful, native trees.

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    1. Thanks, Beth. These desert serviceberries really surprised me--so different from the ones in the Black Hills (A. alnifolia).

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