258 BEECH FAMILY 



thick elliptical cotyledons which remain within the nut during germina- 

 tion. 



A genus of about three hundred species native of the warm parts 

 of the north temperate zone and of the adjacent tropical mountains. 

 About fifty species occur in the United States, twenty-two of which occur 

 in the eastern half of the country. Many oaks are valuable for their 

 hard strong wood, the astringent bark of several species is used in tanning 

 leather and the outer bark of two species from southwestern Europe and 

 northern Africa furnishes the cork of commerce. 



In cultivation oaks are raised from seed. After cutting they renew 

 themselves by the growth of shoots from the stumps. 



1. Leaves lobed, the lobes acute, bristle pointed, acorn ripening the 



second autumn — Black Oaks 



a. Leaves dull green, their lobes cut about half 



way to the midrib, acorn cup shallow Q. rubra 



b. Leaves glossy, their lobes separated about 



three fourths of the way to the midrib, 

 acorn cup about one-half as long as acorn 



(1) Scales of cup loose, pubescent Q. velutina 



(2) Scales of cup appressed, smooth 



(a) Acorn elongated, autumn foliage 



brown Q. ellipsoiialis 



(b) Acorn nearly round, autumn foliage 



scarlet Q. coccinea 



2. Leaves with rounded lobes or crenate or toothed, lobes of teeth not 



bristle-tipped, acorns ripening the first autumn — White Oaks 



a. Leaves deeply round lobed 



( 1 ) Leaves dull, smooth, acorn cup not 



fringed Q. alba 



(2) Leaves glossy above, hairy below, acorn 



cup fringed Q. macrocarpa 



b. Leaves crenate or dentate, not deeply lobed 



( 1 ) Tree, leaves broadly rhombic, acorns 



long peduncled Q. bicolor 



(2) Shrub or small tree, leaves, more than 



twice as long as broad, acorn short 



peduncled Q. pr in aides 



Quercus rubra L inne 1753 Red Oak 



Large tree, 12-24 m. (40-80 ft.) high, 3 dm.-l m. in diameter, (ex- 

 ceptionally in the eastern states, 45 m. high and 2 m. in diameter), trunk 



