Oaks of the World

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  Quercus pennivenia
Author Trel. 1924 Mem. Natl. Acad. Sci. 20:135 1924

diagnosis here
Local names
Range Mexico (E. Sinaloa, SW Durango); 1730-2500 m
Growth habit 5-8 m, trunk 15-45 cm in diameter
Leaves 15-30 cm x 8-30, suborbicular; apex obtuse-round bristle-tipped; base cordate; margin entire or irregularly toothed, with 1-14 aristae, mostly in the apical part of the blade; adaxially glabrous or with some scattered uniseriate hairs and tomentose on veins and axils; abaxially densely pale grey-brown tomentose, hiding the papillose, somewhat bullate epidermis; 7-10 veins pairs; petiole 1.5-3 cm long, tomentose;
Flowers pistillate catkins tomentose, 4-17 cm long, bearing 8-20 acorns clustered at the end;
Fruits acorn circa 1 cm long, 0.7-1 cm wide, ovoid, 1/3 enclosed in a 0.8-1 cm wide cup;

Bark, twigs and

bark of first year twig greyish-yellow tomentose, older twig hairles and grey to black-purple; bud 3-9 mmn ovoid, villose;
Hardiness zone, habitat mineralized, sterile soils in oak-pine forests;

-- Sub-genus Quercus, Section Lobatae, Series Erythromexicanae, Group Racemiflorare (with Q. urbanii, Q. conzatii, Q. tarahumara, Q. radiata and Q. huicholensis);
-- This taxon has been synonymous with Q. urbanii (from which it is morphologically indistinguishable), until the work of R.A. McCauley 2020 showing quite distinct genetic data.

-- Few hybrids known with other oak species (mainly with Q. tarahumara, from which it differs in the mature infrutescence up to 17 cm long vs 1 cm for tarahumara).
-- It can have some of the largest leaves of the Group.

Subspecies and