Quercus macrocarpa Michaux 



BUR OAK 



Oak Family (Fagaceae) 



CONSERVATION STATUS 



U.S. Fish and Wildlife Service: None 



Bureau of Land Management: Sensitive 



Montana Natural Heritage Program: G5 SI ; demonstrably secure globally, but may be 

 critically imperiled in Montana where it is extremely rare. 



DESCRIPTION: Bur oak is a small to large tree. Its bark is deeply furrowed and twigs are stout. 

 The alternate, oblong-elliptic leaves, to 20 cm (8 in) long, are deeply to shallowly lobed with the 

 terminal lobe the largest. They are dark green above, but silvery below with fine, star-shaped hairs. 

 Male flowers of 5-10 stamens are borne in long, loose, pendulous inflorescences from the leaf axils. 

 1 -several female flowers occur in the axils of new leaves. The acorn is 2-4 cm long, ellipsoidal, and 

 the bottom half or more of the acorn is enclosed by a roughened, firinge-margined cup. Acorns 

 mature in one year, often persisting. This is Montana's only native oak. 



GEOGRAPHICAL DISTRIBUTION 



Global distribution: Eastern temperate North America, from New Brunswick to 

 Saskatchewan, south to Maryland, Arkansas and Texas (Great Plains Flora Association 

 1986). This stand is contiguous with Black Hills oak, and is upstream on the Little Missouri 

 River from stands on escarpments and coulee systems that may reflect its relict origin. 



Quercus macrocarpa 

 Bur Oak 



Montana distribution: Carter County. 

 The single stand in Montana straddles 

 he state lines and extends into adjoining 

 Crook County, Wyoming. 



Carter County distribution: The species 



in Montana spans over 1 ,000 acres, but only 



a fraction of this area has an oak-dominated 



plant association, and there are only an 



estimated 12 acres of oak-dominated plant 



association on local BLM-administered lands 



(Heidel 1993). Most of the oak stand is on 



private or state ownership, and many of the oak trees intersperse with other vegetation types. 



The species is concentrated in the area within two miles north of the Wyoming border and 



south of Alzada. An area of oak co-dominance also occurs on a scattered BLM tract along 



Arkansas Creek, tributary of the Little Missouri River. All BLM tracts in the vicinity were 



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