The precise identification of Oaks in the Four Corners area is a subject of much disagreement: the Flora of North America, A Utah Flora, Colorado Flora, Trees and Shrubs of Colorado, and the Synthesis often disagree on the presence or absence of a half dozen species -- except for the unanimous agreement about the ubiquitous Quercus gambelii and the fact that Q. gambelii hybridizes with just about any other Oak, producing a confusion of similar-looking plants.

The first group of photographs below show Quercus turbinella, uncommon in the Four Corners region but typically there a large shrub that retains its Holly-like leaves in the winter.

Quercus welshii, shown in the second group of photographs below, typically has many slender stems and deciduous leaves with more undulating margins.

As you hike the Four Corners states, take a careful look at Oaks and you will find leaf shape and tree height varying widely  --  the result of hybridizing, almost always with Quercus gambelii, Gambel's Oak.

Semi-desert, foothills. Shrublands, openings. Spring.
Canyons of the Ancients National Monument, March 18, 2007.

Quercus turbinella occurs in all of the Four Corners states but is most common in Arizona and New Mexico (as the map below indicates).  It grows to about twenty feet tall but more commonly in its northern limits, as shown here, it is a thick shrub in shape, about six feet by six feet.  It can be solitary, as it usually is in the Four Corners area, or it can form thickets.

"Turbinella" is from the Latin for "a little top" and perhaps refers to the shape of the long, narrow acorn.  Edward Greene named and described this tree in 1889 from a collection he made in Baja California.

Semi-desert, foothills. Shrublands, openings. Spring.
Canyons of the Ancients National Monument, May 28, 2009.

Distinctive leaves are about a half inch wide and an inch long, much smaller than those of the very common Quercus gambelii.  They are pubescent with a number of stellate hairs (i.e., branched in a starburst shape) and they are sharply toothed, giving rise to the common name, "Holly Oak".  The leaves shown here are new; those above are hanging on the tree from the previous year.  Notice the dried pollen chains at the bottom of the photograph at left.

Semi-desert. Shrublands, openings, sand. Spring.
Top two photographs and at left and immediately below: Chesler Park Trail, Canyonlands National Park, Utah, October 17, 2017.
Immediately above: Behind the Rocks Wilderness Study Area, Moab, Utah, October 26, 2012.

Quercus welshii most commonly occurs in deep sands and often no more than a few feet of stem shows above the sand dunes. The stems can be few and scattered in the dunes, or they can be numerous, producing a low thicket.

Leaves and petioles are quite stellate hairy.

Semi-desert. Shrublands, openings, sand. Spring.
Above and left: Lower Butler Wash, Utah, March 15, 2016 and April 20, 2017.

Quercus welshii most often loses its leaves in the fall or winter, but in these photographs, several large thickets of the plant have retained their leaves into the spring when new, light green leaves appear.

Notice also at left and immediately above, the plant is draped in male flowers.

This species was named and described by Robert Denham in 2003 from collections made in San Juan County by Stanley Welsh and Larry Higgins in 1985. The plant had previously been sometimes called Quercus havardii var. tuckeri.

Stanley Welsh is Professor Emeritus at Brigham Young University where he taught for 44 years. Click to read more biographical information about Welsh.