Quercus durifolia Seemen ex Loes.

Mexico (Chihuahua, Durango, Nuevo Leon, Sinaloa, Sonora, Tamaulipas); 1700-2350 m;

2-9 m tall; often taller in cultivation;

3-6 cm long, 1-1.5 wide; evergreen or lately deciduous ; subcoriaceous; lanceolate or oblong-lanceolate; apex obtuse or acute, bristle-tipped; base obtuse or slightly cordate ; margin flat, not revolute, often undulate, mostly entire but with seldom 1-2 aristed teeth near apex; dark grey-green above, hairless except some multiradiate hairs scattered along midrib; greyish green beneath, with an even, dense, short, more or less persistent tomentum, made of fasciculate, undulate, stalkless or shortly stipitate, long trichomes, without glandular hairs; midrib yellow, almost glabrous; 7-11 vein pairs, sometimes slightly impressed; epidermis papillose; petiole 0.5-1 cm long, glabrescent;

in May ; male catkins 3 cm long, with pubescent rachis; male flowers with 6 stamens, and glabrous anthers; female flowers stalkless or nearly so;

acorn ovoid or ellipsoid, 1-1.3 cm long, singly or paired, sessile or on a very short stalk; cup conical to halfround, with light grey hairs, enclosing 1/2 of nut; maturing in 1 year from August to October;

– A. Camus : n° 296; – Sub-genus Quercus, section Lobatae, Series Erythromexicanae; – Differs from Q. eduardii in the entire margin (dentate for eduardii ), and in the undulate rays of the fasciculate hairs (spiraly twirled for eduardii ). – Possible confusion with Q. saltillensis , but this one is glabrescent abaxially, with stellate trichomes only along veins.