Chihuahuan Oak

Quercus chihuahuensis is a distinctive species throughout its range, mostly in dry montane western Mexico; it occurs in the United States only as putative hybrids with Q . grisea (the Eagle and Quitman mountains) and Q . arizonica (Hueco Tanks) in Texas.

Shrubs or trees , deciduous, to 10 m. Bark gray, furrowed, checkered, or scaly. Twigs gray, 2-3(-4) mm diam., densely tomentose. Buds reddish brown, broadly ovoid, distally rounded, 2-2.5 mm, densely yellowish pubescent; scales gray-puberulent; stipules persistent, 1-4, subulate, pubescent, at base of terminal buds. Leaves: petiole 3-5(-8) mm. Leaf blade elliptic or oblong to ovate or obovate, (25-)40-50(-85) × (18-)20-30(-50) mm, base rounded or shallowly cordate, margins entire or toothed to sublobate, secondary veins 8 to 10 on each side, somewhat branching, apex broadly rounded to acute; surfaces abaxially yellowish or grayish, densely stellate with velvety hairs, adaxially green, sparsely soft-pubescent with prominent, spreading, stellate hairs, felty to touch, secondary veins somewhat prominent on both surfaces, even under dense tomentum. Acorns 1-3 on tomentose peduncle 15-35(-60) mm; cup hemispheric, 7-10 mm deep × 10-15 mm wide, enclosing 1/2 nut, scales proximally thickened, distally appressed, densely gray-puberulent, tips reddish, ultimately glabrate; nut ovoid, 14-18 × 10-12 mm, puberulent, eventually glabrate. Cotyledons connate.

Tex.; Mexico (Chihuahua, Sonora, Zacatecas, and San Luis Potosí).

Flowering spring.

Oak and pinyon-juniper woodlands, grassy hills, sometimes extending into dry thorn scrub and bursera woodland (Mexico); 400-2000m.

Quercus infralutea Trelease; Q. jaliscensis Trelease; Q. santaclarensis C. H. Muller