Quercus tinkhamii C.H.Mull.

Mexico (Hidalgo, San Luis Potosi, Nuevo Leon, Tamaulipas); 1400-2400 m;

small tree;

2-4.5 x 1-2.7 cm; deciduous; subleathery; obovate, oblanceolate, oblong or elliptic; apex obtus to rounded, with dark mucro; base obtuse to subcordate, seldom acute; margin thickened, not revolute, slightly undulate, entire or mostly with 2-5 pairs of prominently, long mucronate teeth except near the base; adaxially green, lustrous, hairless or glabrescent with some scattered glandular hairs and stalkless, stellate ones at base of midvein; abaxially green, pubescent to glabrescent, with not appressed stellate trichomes, and most often hyaline glandular ones; 6-9 vein pairs not or very slightly prominent above, raised beneath; epidermis papillose; petiole 2-4.5 mm long, pubescent;

in July; male catkins 2 cm long, few-flowered; female ones 0.5 cm, with 1-2 pubescent flowers;

acorn 1-1.5 mm long, ovoid, singly or paired; stalkless or on a 2-5 mm long peduncle; cup half-round to slightly patelliform, with straight rim, 1-1.2 cm wide, with pubescent scales, enclosing 1/3 or 1/4 of the nut; maturing same year, in September-October;

– Sub-genus Quercus, Section Quercus , Series Leucomexicanae; – Endangered species; – Also written tinkhami; – Possible confusion with Q. sebifera which is also a low shrub; but sebifera has leaves waxy-glaucous on the abaxial blade surface, and the margin has only shortly mucronate teeth. – May be confused as well with Q. vaseyana , which is taller, with leaves 3-7 (-9) cm long, toothed from base to apex, and appressed stellate trichomes beneath; – Q. grisea differs in having 2 sizes of stellate trichomes abaxially, and its height (a tree rather than a low shrub)