Description from Flora of China
Quercus rex Hemsley, Hooker’s Icon. Pl. 27: t. 2663. 1901.
Trees to 30 m tall. Branchlets pale brown tomentose, glabrescent. Leaves often crowded apically on branches; petiole 2-3 cm, brown tomentose; leaf blade obovate to obovate-oblanceolate, 15-20(-27) × (4-)6-9 cm, densely brown tomentose when young, glabrescent, base cuneate, margin apically remotely minutely serrate, apex shortly acuminate to acute; midvein and secondary veins abaxially prominent but adaxially impressed or flat; secondary veins 18-22 on each side of midvein; tertiary veins abaxially evident. Cupule saucer-shaped, 1.5-1.8 × 3.5-5(-6) cm, enclosing 1/3-1/2 of nut, outside and inside tawny tomentose, wall to 4 mm thick; bracts in 7 or 8 rings, margin entire or sinuate, basal ones free from wall. Nut oblate, 2.5-3.5 × 3.5-5 cm, pale grayish orange tomentose when young, apically and basally hairy with age, apex rounded to impressed; scar 2-2.5 cm in diam., depressed; stylopodium often deciduous. Fl. Apr-May, fr. Oct-Nov.
Dense forests in valleys; 1100-1800 m. S to W Yunnan [NE India, Laos, Myanmar, Vietnam]