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

Quercus chihuahuensis, the Chihuahua oak, is a species of oak in the beech family. It is native to the region from extreme western Texas west to Sonora, Mexico, and south to Zacatecas and San Luis Potosí. It grows mostly at mid elevations, from 400–2,000 metres (1,300–6,600 feet) above sea level, in forests mixed with various pines and other oaks. It is one of the dominant species of the Sierra Madre Occidental in Chihuahua and Sonora.

The tree grows up to 10 m (33 ft) tall, very common in much of its range. The leaves are entire to toothed or sublobate, green on the top but yellow or gray on the underside because of a coating of velvety, stellate (star-shaped, highly branched) hairs. The species is related to Quercus arizonica and Quercus grisea, sometimes hybridizing with these two species in Texas.