Quercus coahuilensis Nixon & C.H.Mull.

Mexico (Coahuila, Chihuahua); 2000-3550 m;

may sometimes reach more than 5-6 m tall; trunk to 0.25 m in diameter;

2-6 cm long, 1-3 wide; persistent 2 years; leathery; obovate or elliptic-oblong; base cordate or rounded; apex acute or rounded, aristate; margin flat or slightly revolute, with apically 2-4 pairs of bristle-tipped teeth; yellowish green, hairless above except along veins; densely tawny tomentose below (tomentum hardly scratchable, made of fasciate, entangled hairs); 4-8 vein pairs, impressed adaxially, prominent beneath; midrib becoming often pinkish; short grey tomentose petiole, 3-6 mm long;

staminate inflorescence 2 cm long, flowers with anthers purple-red becoming yellow; pistillate inflorescence 1-flowered, rarely 2, on a 1-4 mm long tomentose peduncle;

small acorn, most solitary; maturing in 2 years; cup with a short peduncle (3-4 mm), half-round, with smooth, thin, appressed scales ciliate at margins; cotyledons free;

hardy;

– Sub-genus Quercus, section Lobatae, Series Erythromexicanae; – Closely related to Q.hypoxantha , with which it forms the “ Quercus hypoxantha complex “, in association with Q.hintoniorum and Q.miquihuanensis . – Specimens morphologically intermediate between Q.coahuilensis and Q.gravesii have been collected in the Chisos Mountains of Texas ( Q.tardifolia C.H.Mull.) although Q.coahuilensis does not exist in the Chisos Mountains (but it is not far, in adjacent Coahuila, so pollen may have infiltrated Texas…).