Quercus welshii: Clonal, deciduous, sand-binding shrubs, or, less commonly, small trees to 2 m or more; leaves densely grayish to yellowish stellate-hairy on both sides when young, less densely so in age, but only slightly, if at all, paler beneath than above, even in age, 1.5–5.5 cm long, 0.9–3.3 cm wide, oblanceolate to elliptic in outline, with usually 6–10 toothlike lateral lobes, these typically apiculate-acuminate and sometimes further notched or toothed apically; catkins 1–2.5 cm long; involucral cups 7–10 mm long, 14–18 mm wide, subsessile, ca 1/4–1/3 the length of the acorn, clothed with imbricate, densely hairy scales; acorns 15–23 mm long, 14–18 mm thick.

Quercus welshii R. A. Denham, A Utah Flora, ed. 3. 317. 2003. [based on: Q. havardii var. tuckeri S. L. Welsh, Great Basin Naturalist 46: 109. 1986; Type: Utah, San Juan Co., Low Pass, e. of Kens Lake, S. L. Welsh & L. C. Higgins 23630, 10 Jul 1985, holotype BRY; Q. undulata authors, not Torrey]