Oaks of the World

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  Quercus douglasii
Author Hook. & Arn. 1840
Synonyms gambelii Liebm. 1854, not Nuttal 1847
oblongifolifa var. brevilobata Torr. 1874
ransomii Kellogg 1873
Local names blue oak; iron oak;
Range California from 100 to 1200 m ;
Growth habit 5-18 m; trunk 25-40 cm in diameter, most often single; open, rounded crown;
Leaves 3-8 x 2-4 cm; deciduous; stiff; oblong; rounded at both ends; margins somewhat wavy, entire, or shallowly 4-5 lobed, sometimes coarsely dentate; dark blue green above, pale yellow green beneath; small, stellate trichomes; petiole 0.3-1.2 cm, blue green;
Flowers February to April;
Fruits acorn solitary, 2-3 cm, elliptic, sessile or nearly so; very shallow cup covered with small warty scales; matures in 1 year; kernel sweet;

Bark, twigs and
buds

bark light grey, scaly; twigs reddish or yellowish, hairy at first, becoming glabrous; bud subglobose, red brown, 3-5 mm long, scales glabrous but with ciliate margin;
Hardiness zone, habitat quite hardy; prefers sunny sites and calcareous, dry, rocky soils; lives up to 200 years;
Miscellaneous -- Camus : n° 258 ;
-- section Quercus;
-- resembles Q.lobata (leaves much more lobed, without blue color); resembles too Q.x alvordiana (leaves more leathery, smaller, semi-evergreen);
-- wood hard, heavy;
-- discovered by David Douglas (1798-1834), Scottish botanist;
-- hybridizes with Q.lobata (= x jolonensis), Q.garryana (= x eplingii ), and Q.john-tuckeri (= x alvordiana)
Subspecies and
varieties
 
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