Oaks of the World

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 Quercus obtusata
AuthorHumb. & Bonpl. 1809
Synonyms alvarezensis Trel.
atriglans Warb.1939
crenatifolia Trel. 1924
hartwegii Benth. 1840 (Camus = n° 225)
hartwegii f. glabrata Trel. 1924
innuncupata Trel. 1924
obtusata var. hartwegii A.DC 1864
pandurata var. hartwegii Wenz. 1884
pandurata Humb. & Bonpl. 1809
panduriformis Trel. 1924 (A. Camus = n° 234)
rugosa sensu Trel., not Née
spicata Bonpl. 1809 not Sm 1916
Local namesencino calicahuac; encino cosahuicahuatl; uricua; charari; tocuz;
Range Mexico (Aguascalientes, Guerrero, Durango, Guanajuato, Hidalgo, Jalisco, Mexico, Michoacan, Morales, Nayarit, Oaxaca, Puebla, Queretaro, San Luis Potosi, Tlaxcala, Veracruz, Zacatecas); 620-2800 m;
Growth habit 7-25 m tall; trunk to 20-40 cm in diameter;
Leaves 8-16 x 4-12 cm ; deciduous ; more or less broadly oboval, or oblong-oboval; thick, not very rough nor coriaceous; sometimes convex; apex rounded or obtuse, mucronate; base rounded to cordate, often asymmetrical; margin flat, crenate rather than dentate (if so, 5-9 pairs of teeth ending in a short, stout mucro, bending toward the abaxial side), never entire; olive green, lustrous above, with fascicled, stellate and simple glandular hairs mainly at base of midrib, glabrescent; beneath pale green, dull, tomentose mostly on veins (tomentum made of 5-8 rays fascicled, sessile or not, trichomes, and numerous amber or reddish glandular hairs, and abundant glandular secretions); 9-12 vein pairs slightly impressed above; epidermis whitish-papillose, remotely bullate; petiole hairy 5-15 mm;
Flowers in April-May; staminate inflorescences 3-10 cm long, with numerous flowers; pistillate flowers pubescent, 3 to 15 or more, near the tip of a pubescent, 14 cm long peduncle;
Fruits acorn 1.6 cm long, globose, sometimes ovoid; apex rounded, mucronate; single or 2-3 together (to 10); peduncle slender, hairy, 2-5 cm long; enclosed 1/3 to 1/2 by cup; cup half-round 1.5-2 cm in diameter, with loose, appressed, grey tomentose scales; maturing in 1 year from August to November; edible;

Bark, twigs and
buds

bark fissured into plates; twigs slender (1-4 mm thick), grey or black with stellate and glandular trichomes, glabrescent; numerous pale lenticels; buds ovoid, grey brown, 2-5 mm, scales ciliate at margin; stipules linear, 3-9 mm long, pubescent, deciduous;
Hardiness zone, habitat zone 8;
Miscellaneous -- A. Camus : n° 233 ;
-- Section Quercus;
-- Q. alvarezensis is, for Govaerts (2007) synonym of Q. rugosa Née...
-- Q.spicata Sm 1919 is actually Lithocarpus spicatus (Sm) Rehd. 1919
-- Resembles Q. potosina which has smaller leaves (3-10 x 2-6 cm); resembles too Q. rugosa, this one has a convex leaf strongly coriaceous, a revolute margin, the epidermis bullate; at least, one can differenciate Q. obtusata from Q. laeta which has foliar underside glaucous, without masses of glandular secretions, none or rare glandular trichomes, a leaf more oblong than oboval with a margin sometimes entire.
Subspecies and
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