Quercus porphyrogenita Trel.

Mexico (Nuevo Leon, Tamaulipas); 700-1350 m;

5-8 m;

2-8 x 1-3 cm; leathery; oblong; apex rounded or obtuse, sometimes retuse; base subcordate, cordate to obtuse; margin flat, entire, sometimes crenate; adaxially glaucous, lustrate, hairless or with some fascicled, sessile hairs at base of midrib; abaxially glabrous or nearly so, with a few sessile, fascicled hairs at base; 8-18 vein pairs, slightly curved, inconspicuous above; epidermis slightly papillose; petiole 2-4 mm long, glabrescent;

April; male catkins 5-7 cm long, with pubescent rachis; flowers with 4-7 stamens and hairless anthers;

acorn ovoid 1.5-2 cm long, solitary or paired; sessile; enclosed 1/4 to 1/3 by cup; cup half-round 11-13 mm wide; maturing in 1 year in July-August;

– Sub-genus Quercus, Section Quercus, Series Leucomexicanae; – In 2006 was considered by S. Valencia as a synonym of Q. germana , but in 2016 the same Author recognized it as a true species. – Possible confusion with Q. laceyi : both have glaucous, glabrous leaves; however laceyi has the foliar margin mostly lobed, the apex retuse, the base usually cuneate (sometimes rounded), and the upper side dull.