145 



BLACK JACK OAK. 



Quercus marilandica, Muench. 



FORM This tree usually attains a height of 20-30 ft. with a diameter of 18 inches, but may 

 reach a height of 60 ft. with a diameter of 3 feet. It reaches its maximum size in Texas 

 and Arkansas. Crown usually compact, round-topped, and narrow on account of short branches. 

 Upper blanches are ascending, lower ones spreading. 



BARK Thick, roughened by deep flissures which separate broad angular plates covered with 

 dark brown to nearly black scales. 



TWIGS Stout, coated at first with pale woolly covering of hairs, later becoming smooth 

 and dark brown to gray. 



BUDS Alternate, ovate, distinctly angular, sharp-pointed, 1 of an inch long, reddish-brown 

 and rusty pubescent. 



LEAVES Alternate, simple, broadly ovate in outline, 6-7 inches long with an almost equal 

 width, rounded or heart-shaped at the base, 3-5-lobed. Mature leaves deep green, thick, 

 leathery, and smooth above; often rusty brown below. 



LEAF-SCARS See "Loaf-Scars" under White Oak, page 132. 



FLOWERS Appear about May when the leaves are J developed. Staminate flowers in 

 slender, often persistent aments 2-4 inches long. Pistillate flowers on short, stout, pubes- 

 cent stalks. 



FRUIT An acorn, maturing at the end of the second season, solitary or paired, short 

 stalked. Nut ovoid 2 of an inch long, nearly same width throughout, often striate, light 

 brown. Cup hemispheric, deep, covers one-half or over of nut, light brown and downy on 

 inside, covered by large reddish-brown loosely overlapping scales. Small scales form a thin 

 rim around the margin. 



WOOD Ring-porous; with conspicuous medullary rays; dark brown, heavy, hard, strong. 

 Weighs 45.64 Ibs. per cubic foot. Used for fuel, charcoal, and manufactured into lumber 

 to a limited extent. 



DISTINGUISHING CHARACTERISTICS The Black Jack Oak, also known as Jack Oak and 

 Barren Oak, can be distinguished by the large obovate leaves which are usually 3-5-lobed above 

 the middle, or sometimes entire and covered with rusty brown pubescence. It is the only 

 Oak of Pennsylvania which has its leaves dilated near apex. Its sharp-pointed, distinctly 

 angular and somewhat hairy bud and its hemispheric acorn cup also aid in distinguishing 

 it from the other closely related species. 



RANGE New York and Pennsylvania west to Nebraska and south to Florida and Texas. 



DISTRIBUTION IN PENNSYLVANIA Occasional in the eastern and southern parts of the 

 State and a few local outposts in the western part. 



HABITAT Usually found on poor, dry, sterile, sandy soil, but in the South it is also found 

 on clay. It reaches its best development upon the rich soil in the southern part of its 

 distribution. 



IMPORTANCE OF THE SPECIES In the North it is a shrub only or a small tree of no 

 commercial importance, while in the South it becomes somewhat larger and is used for fuel, 

 charcoal, and lumber. In Pennsylvania it is of no forestal importance, but is a very attractive 

 tree for ornamental purposes on account of its compact and deep crown. 



10 



