Oaks of the World

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  Quercus macrocarpa
Author Michx. 1801 Hist. Chênes Amér. 2
Synonyms macrocarpa var. oliviformis (F.Michx.) A.Gray 1856
macrocarpa subsp oliviformis (F.Michx.) A.Camus 1935
macrophylla hort. not Née
oliviformis F.Michx. 1811
ramosa Booth
Local names mossycup oak ; burr oak ; Northern overcup oak ;
Range Eastern USA; to 1000 m and more; introduced in Europe in 1795;
Growth habit 20 m tall (may reach 30 m); crown spreading; stout trunk 0.6-1.2 m in diameter;
Leaves 10-15 (30) x 5-13 cm; oblong; narrower near midblade; apex rounded; base cuneate; 5-9 deep lobes; lustrous green above; greyish tomentose beneath; 4-5 vein pairs; petiole 1.5-2.5 cm long;
Flowers pistillate and staminate flowers in early spring;
Fruits acorn 2.5-5 cm long; oval; pubescent at apex; stout peduncle 1-2 cm long; cup hairy, deep (enclosing 1/2 or more of nut), purplish, 2 cm in diameter; cotyledons distinct; maturing in 1 year;

Bark, twigs and
buds

bark yellowish grey, shiny, becoming furrowed, rough, dark brown; twig pubescent, sometimes with corky ridges; buds 2-5 mm long, glabrous;
Hardiness zone, habitat hardy; all types of soils, including calcareous ones; reaches 150 years old;
Miscellaneous -- A. Camus : n° 279 ;
-- Sub-genus Quercus, Section Quercus, Series Prinoid;
-- Related to
Q.bicolor ;
-- Hybridizes with : Q. alba (= x
bebbiana), michauxii (= x byarsii), muehlenbergii ( = x deamii), stellata (= x guadalupensis), lyrata (= x megaleia), bicolor (= x schuettei) ;

Subspecies and
varieties
-- var. depressa (Nuttall) Engelm. 1876 Trans. Acad. Sci. St. Louis 3: 382
= Q. obtusiloba var depressa Nutt. 1818
= Q. stellata var. depressa (Nuttal) A.DC 1864
= Q. macrocarpa f. depressa (Nutt.) Trel. 1924
= Q.mandanensis Rydb. 1931
Minnesota, North Dakota; Colorado;
probably just a geographic race...

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