Oaks of the World

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  Quercus sideroxyla
Author Humb. & Bonpl. 1809
Synonyms omissa A.DC. 1864
Local names encino colorado;
Range Mexico (Aguascalientes, Chihuahua, Coahuila, Guanajuato, Jalisco, Michoacan, Durango, Nuevo Leon, San Luis Potosi, Tamaulipas, Zacatecas); 2200-3000 m;
Growth habit 5-10 m tall, reaches 20; trunk to 0.5-1 m in diameter;
Leaves 3-6 (-8) x 2-4 cm; thick, coriaceous, rough; oblong-oboval; apex obtuse or acute, aristate; base cordate or round; marginflat, thickened, cartilaginous, dentate-serrate with 2-5 pairs of teeth shortly bristle-tipped; yellowish green above, dull, glabrescent except at base of midrib where remain some stellate, stalkless, dark trichomes; dense, yellowish-white felted tomentum beneath, made of long, sessile, stellate trichomes and golden glandular hairs; reticulate, bullate and papillose epidermis; 5-9 vein pairs slightly raised above, prominent beneath; petiole blackish tomentose, 5-8 mm long;
Flowers from June to August; staminate catkins tomentose, 3-4 cm long, with more than 20 flowers; pistillate inflorescences 0.5-1 cm, with 1-2 flowers;
Fruits acorn 1-1.2 cm long, ovoid sessile or sometimes with a stalk to 3-5 mm long; singly or paired; cup half-round 8-10 mm in diameter, enclosing 1/3 ou 1/2 of nut ; maturing in 2 years between November and January;

Bark, twigs and

bark greyish, thick, furrowed; twigs 1.8-2.5 mm thick, at first tomentose, becoming hairless second year, pinkish brown, with inconspicuous lenticels; buds 2.5-4 mm long, ovoid, reddish brown; stipules pilose, deciduous;
Hardiness zone, habitat not quite hardy; inhabits dry, rocky sites;
Miscellaneous -- A. Camus : n° 368;
-- Section Lobatae;
resembles Q. crassifolia, but differs in having the abaxial tomentum less dense, and made of stalkless trichomes (pediculate for crassifolia), and the tomentum of twigs less dense as well;
Subspecies and
For Trelease : f. aquifolia and f. ciliifera;