Oaks of the World

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  Quercus grisea
Author

Liebm. 1854 Overs. Kongel. Danske Vidensk. Selsk. Forh. Medlemmers Arbeider 1854: 171

Diagnosis here

Synonymsundulata Torr. var. grisea (Liebm.) Engelm. 1877
oblongifolia Coult., not Torr. 1853, nor R.Br. ter 1871
Local namesscrub oak, gray oak ; mountain white oak ;
Range Southwest Texas; North and Center of Mexico; 1500-2700 m;
Growth habit4-7 m, sometimes to 10 m, but smaller in cultivation; trunk short, 10-30 cm wide;
Leaves

2-4 x 1-3 cm; semi-evergreen; thick, stiff; oboval or oblong-elliptic; apex pointed or obtuse, mucronate; base rounded to cordate; margin flat, entire, or often when youth crenate-dentate, with 1-4 pairs of mucronate teeth; glaucous grey, slightly lustrous above with stalkless, stellate hairs; greyish green , hairy beneath, with dense, stalkless, stellate trichomes; 6-10 vein pairs, remotely raised above or sometimes slightly impressed, prominent beneath; epidermis papillose; petiole pubescent, 2-8 mm long;

Flowers in April; male catkins 4-7 cm long, with more than 20 pubescent flowers; female inflorescences 1-4 cm, with 1 to 8 flowers slightly tomentose;
Fruits acorn 1.2-2 cm long; singly or paired or more; short peduncle 0-3 cm long; cup half-round, greyish tomentose, enclosing 1/2 of nut; cup scales with base thickened; maturing in 1 year from October to December; cotyledons connate;

Bark, twigs and
buds

bark light grey, furrowed into plates; young twigs smooth, yellowish tomentose, glabrescent; buds dark red brown, ovoid, glabrous, 1-2 mm long, covered with yellowish stellate hairs; persistent stipules, 3-6 mm long, pubescent;
Hardiness zone, habitatzone 7-8; prefers dry, rocky soils;
Miscellaneous-- A. Camus : n 179;
-- Sub-genus Quercus, Section Quercus, Series Leucomexicanae;
-- Possible confusion with Q. chihuahuensis but this species has abaxial foliar trichomes fascicled stipitate;
-- Q. grisea can as well be confused with Q. microphylla and Q. frutex; however Q. grisea can be distinguished from both species by its tree habit, and densely velutinous leaves with appressed stellate trichomes which completely cover both surfaces. Q. microphylla and Q. frutex are shrubs and have leaves with fasciculate trichomes on the abaxial blade surface. Additionally Q. frutex has leaves with revolute margins while those of Q. grisea have flat margins.
Subspecies and
varieties

Q.grisea is actually a complex of two species :

--- 1/ Q.grisea Liebmann
= gray oak, mountain white oak ;
it is the type described above;
the specimens named Q.endemica C.H.Muller 1937 are actually identical;
several hybrids with : Q.gambelii, Q.mohriana, Q.arizonica, Q.turbinella;

---2/ Q.arizonica Sargent 1895 : see this word

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