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Plant Focus

Quercus tonduzii with acorn
An oak found only on a volcano in Costa Rica

Scouting for Quercus welshii

Quercus welshii is found in sand shinnery ecosystems on Navajo Nation and Bureau of Land Management (BLM) lands in northern Arizona and southern Utah. For some authors, this oak represents the western distribution of Q. havardii or it is given varietal status as Q. havardii var. tuckeri. The IUCN Red List reports Q. havardii as Endangered1. Major threats include disturbance from tourism or recreation and climate change, especially as the region continues to face a "megadrought".

Forming acorns and leaves near Moab
Quercus welshii leaves with forming acorns in a population near Moab in eastern Utah © Cindy Newlander

Through an American Public Gardens Association/US Forest Service Tree Gene Conservation Partnership Grant awarded in fall 2021, I have been afforded the opportunity to visit multiple populations of Q. welshii this year, first through a scouting trip completed in May and later in August through a collecting trip where I will be collaborating with staff from Huntington Museum, Library, Art Museum, and Botanical Gardens and The Arboretum at Flagstaff. The purpose of the grant program is to add more collections of rare or difficult-to-propagate species into ex-situ collections at botanical gardens. Thanks to work by Dr. Sean Hoban at The Morton Arboretum in 2016, the number of plants in living collections has increased greatly, from two known collections of wild origin to multiple wild collections grown from acorns accessioned at several US institutions. During the current funding cycle, the aim is also to collect rhizomes and acorns. These collections will be shared with eight partner institutions, either as acorns or as rooted cuttings.

On May 23rd, I met Dr. Ross McCauley, professor of biology and herbarium curator at Fort Lewis College in Durango, and we embarked on a quest to visit populations of this oak species. Over four days and 800 miles, we visited sites on Navajo Nation, BLM, and Bears Ears National Monument lands. Though it was not my first time seeing the oak in the wild, it was my first time visiting it during the growing season. After a short drive into Arizona we pulled off the highway at an unassuming spot near Mexican Water in the Navajo Nation. Here Q. welshii was growing on low dunes of sandy red soil while Coleogyne ramosissima, Eriogonum wetherillii, Linum aristatum, and Ipomopsis gunnisonii bloomed nearby. The signs of drought in this area were obvious—Sphaeralcea sp. plants that had flowered but did not progress to fruit had dried, preserving the flowers’ bright orange color. The 1- to 2-meter-tall oaks in this area did show signs of staminate flowers, and hopefully we will find acorns to collect during the return trip.

Dune site south of Kayenta AZ
Low-growing Quercus welshii on a dune site south of Kayenta, Ariz. © Cindy Newlander

Our next stop was south of Kayenta, Ariz. where there was a wash that could have doubled as a drive for a small vehicle. It was topped with large dunes with sizeable masses of low-growing oak to about 0.5 meters in height. Very few flowering plants were observed in this area, the most obvious associated taxa being a grass species.

On our second day we headed north into Utah. A small population in Monument Valley was visited that edged a pinyon-juniper2 habitat dotted with blooming yucca (Yucca sp.) and prickly pear (Opuntia sp.). Next, we visited the most distinctive population of the trip in the Glen Canyon National Recreation Area on top of Cedar Mesa. Here the oaks grew to only ankle height in packed red sandy soil with small rocks and not in dunes as in the previous sites. The mesa top also had many slickrock areas where blackbrush (Coleogyne ramosissima) was growing out of the cracks. Ephedra (Ephedra sp.) and juniper (Juniperus sp.) were also growing in this area. Heading farther west, we crossed the Colorado River and visited a site along Highway 276 where Q. welshii was abundant in large sand dunes.

Low growing Cedar Mesa population
Ankle-height oaks on top of Cedar Mesa, Utah © Cindy Newlander

Day three took us to the Moab area. The first site was near Sand Flats Recreation Area, a popular jeep and mountain biking area. Sandy soil and slickrock dominated the landscape alongside Q. welshii, ephedra, blackbrush, and artemisia (Artemisia sp.). This area appeared to have had some precipitation in recent weeks, and there were several species of wildflowers blooming in the area we surveyed. We were also excited to observe acorns forming on these oaks, which had been a rarity thus far. A second stop north of Moab adjacent to Arches National Park also showed small acorns forming. There were observed variations in oak height here as well, with some specimens nearing 2 meters while others were merely ankle height above the dunes.

On our last day we surveyed one final location near Comb Ridge on the south end of Butler Wash. Here the oaks were about a meter in height and showing signs of acorns forming. This site was dominated by slickrock and red sandy dunes that quickly transitioned into the ridge, a monocline that tilts at a 20-degree angle and dates back 65 million years.

This scouting trip allowed me to become more familiar with Quercus welshii and its typical habitat, while also helping me to have manageable expectations for the August collecting trip. I would like to thank the American Public Gardens Association and US Forest Service for funding these efforts, Ross McCauley for sharing his knowledge of the sites, and Sean Hoban and The Morton Arboretum for the efforts they have put into researching and collecting this species in the past.

1 The IUCN Red List assessment is based solely on the populations in Texas, Oklahoma, and New Mexico; Q. welshii is treated as a synonym of Q. havardii.

2 Pinyon–juniper woodland is a vegetation type of Western United States higher elevation deserts, characterized by being an open forest dominated by low, bushy, evergreen junipers (Juniperus osteosperma, J. californica, J. grandis), pinyon pines (Pinus monophylla, P. edulis), and their associates.