Quercus tarahumara Spellenb.

Mexico, in the North of the Sierra Madre Occidental (NE Sinaloa, NW Durango, NE Sonora, W Chihuahua); 1400-2000 m;

reaches 12 metres tall;

8-25 cm x10-20; broadly oboval to almost rounded; convex, thick, leathery; apex rounded or obtuse, aristate; base obtuse to heart-shaped; margin thick, revolute, cartilaginous, entire or dentate, with 4-18 pairs of small aristate teeth; dull olive green above, almost glabrous, with some stalked, stellate hairs along midvein; densely yellowish tomentose beneath with numerous golden glandular hairs and stalked stellate hairs mixed; 7-11 vein pairs; epidermis smooth, papillose; petiole hairy 1.5-6 cm long;

in February; male catkins 10-20 cm long, with numerous flowers; pistillate inflorescences 1 cm long, few-flowered;

acorn ovoid, 0.8-1.4 cm long; solitary or paired on a peduncle less than 1 cm long; cup half-round, 1 cm in diameter, slightly hairy, enclosing 1/3 of nut; maturing in 1 year in June;

not hardy;

– Sub-genus Quercus, section Lobatae, Series Erythromexicanae, Group Racemiflorae; – Related to Q.urbanii which differs mainly in having 3 to 9 acorns on a 4. 5-15 cm long infrutescence, and in living in the South of the Sierra Madre Occidental;