Oaks of the World

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  Quercus hypoxantha
Author

Trel. 1924 Mem. Natl. Acad. Sci. 20: 170

Diagnosis here

Synonyms errans fo. gracilirarmis C.H.Muller 1936
Local names  
Range Mexico (Coahuila, Nuevo Leon, San Luis Potosi, Tamaulipas); 2100-2950 m;
Growth habit usually less than 3 m tall;
Leaves

3-5 cm long, 1.5-2.5 wide; semi-evergreen; leathery; oboval; often folded lengthwise; apex acute or obtuse, aristate; base varying : usually cordate; margin thick, revolute, wavy, with 1-4 pairs of sharp, bristle-tipped teeth in the apical half; light green or grey green (sometimes darker) above, with minute, scattered hairs of various types except glandular; abaxially with dense, woolly, yellow-pinkish tomentum (made of fascicled hairs and golden uniseriate glandular ones, both of them evenly and equally laid out), persistent but easily scratchable, sometimes desappearing with age, covering all the limb including the 6-8 vein pairs; midrib and lateral veins impressed above; epidermis usually bullate ; petiole 0.5 cm long, reddish, glabrescent; 

Flowers in June; male inflorescence 5-6 cm long, with more than 20 flowers; pistillate inflorescence less than 1 cm long, with 1 or 2 flowers, stalkless or on tomentose peduncle 1-4 mm long;
Fruits acorn ovoid, 1-1.5 cm long; solitary, sessile or on a 2-3 mm long peduncle; cup half-round with rounded, flat, tomentose scales; cup enclosing 1/2 of nut; maturing in 2 years in September; cotyledons free;

Bark, twigs and
buds

bark smooth, dark grey; twig slender, thin (to 2.3 mm in diameter), persistently yellowish pubescent, with inconspicuous lenticels; very small bud (2 mm long), ovoid globose, glabrous, with ciliate scales; stipules 2 mm long, seldom persistent;
Hardiness zone, habitat probably hardy zone 7;
Miscellaneous -- A. Camus : n° 367;
-- Sub-genus Quercus, section Lobatae;
-- Related to Q.hintoniorum (which differs in having the abaxially not glandular trichomes only at the vein axils, and cupules covering only 1/4 or 1/3 of the nut); it forms the "Quercus hypoxantha complex Nixon & Muller 1993", in association with mainly Q. hintoniorum, Q.coahuilensis and Q.miquihuanensis, and less often with Q. galeanensis, Q. saltillensis and Q. jonesii.
Subspecies and
varieties
 
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