Quercus gambelii Nutt.

S.W. USA.; North Mexico; 1200 m - 3000 m; introduced in Europe in 1894;

may reach 20 m tall if single trunk, but more often shrubby, 5 m tall, spreading, multiple trunks;

5-15 x 3-8 cm; papery; ovate to obovate or oblong to elliptic; apex rounded; base cuneate or truncate; margin with 3-6 lobes each side, lobes entire or dentate, with an entire or dentate apex, the sinuses between lobes reaching more than half-way to the midrib; lustrous dark green, glabrous above or with some short, sparse hairs; paler, tomentose beneath with 2-5 rayed stellate hairs; red when unfolding; 4-6 vein pairs, slightly raised adaxially, prominent beneath; petiole 1-2 cm, slightly pubescent;

April to June; male inflorescences 2-3 cm long, flowers with 5-7 stamens; female inflorescence 0.3-0.8 cm, bearing 1-3 flowers;

acorn 1.2-2.5 cm; ovoid to ellipsoid; singly or paired; subsessile or very shortly stalked; deep, warted, thick cup enclosing to 1/2 or more of nut; maturing in 1 year;

hardy; prefers dry sites;

– A. Camus : n° 273; – Sub-genus Quercus, Section Quercus, Subsection Dumosae; – William Gambel (1821-1849) was botanist at Philadelphy; – Numerous hybrids exist, creating a hybrid population named “ Q.x undulata complex “ by Little in 1979, to replace the term Q.undulata Torr. 1827; the latter term was applied to a species named “wavyleaf oak”, or “Rocky Mountain shin oak”; J.M. Tucker, in 1971, had yet identified the main parents of this species : Q. turbinella , Q.grisea , Q.havardii , Q.mohriana , Q arizonica, Q. gambelii and Q.muehlenbergii; hybrids between Q. gambelii and an evergreen species are often semi-evergreen; – The name “undulata” inspired numerous authors ! One can find among them : Q.undulata Engelm 1878 (= Q.sinuata Walt.), Q.undulata Kit.1863 (= Q.pubescens Willd.), Q.undulata Benth. 1841 (= Q.benthamii A.DC), Q.undulata K.Koch 1847 (= Q.lusitanica Lam.), Q.undulata Torr 1827 (= Q.x undulata complex Little 1979), Q.undulata Sarg., et A.DC ( = more or less Q.x pauciloba …), Q.undulata S. Wats. (= Q.gambelii Nutt.) ; – For some Authors (Spellenberg 1998, S.Valencia-A. 2004), Q.lesueuri is a hybrid between Q.gambelii and Q.arizonica Sarg. (therefore is a synonym of Q.x undulata ).