28 MISSOURI BOTANICAL GARDEN BULLETIN 
Habitat: wet bottom-land, Maryland to Florida, west to 
Missouri and Texas. 
Quercus macrocarpa (bur oak).—This is the largest of our 
native oaks, usually attaining a height of from 90 to 100 feet, 
occasionally 150 feet, with a trunk diameter of 7 feet. It has 
broad, spreading branches if grown in the open. Its wood 
is particularly adapted for quarter-sawing on account of its 
conspicuous medullary rays, and is considered even better 
than white oak if grown in rich soil. Commercially it is used 
for the same purposes as the white oak. 
The bur oak is the most picturesque American oak as well 
as the most ornamental. It is comparatively easily trans- 
planted when young, and its adaptability to different re- 
gions and climates is remarkable, growing in the forests of 
Canada, in the moist climate of New England, and in the hot 
arid regions of Texas. It is the most rapid-growing of the 
white-oak group and more resistant to a smoky atmosphere 
than any other oak. It may be recognized by its unique 
leaves which have deep rounded sinuses that reach nearly 
to the midribs and divide the leaves almost into 2 parts. The 
pubescence on the lower side of the leaves and corky projec- 
tions on the young branches are also characteristic, as are 
the large-fringed acorn cups and the persistent leaves. The 
bark is grayish brown, deeply furrowed, becoming scaly. 
One of the largest trees in the vicinity of St. Louis is 
located at East Prairie, Missouri. This giant species stands 
about 130 feet in height, and the circumference, measured 3 
feet from the ground, is 23 feet. These measurements and 
photograph reproduced in plate 2 were obtained through the 
courtesy of Mr. R. A. Doyle, of East Prairie, Missouri. 
Habitat: rich moist soil, Nova Seotia to Montana, south 
to Pennsylvania, Tennessee, and Texas. 
Quercus macrocarpa var. olivaeformis (bur oak variety ).— 
This variety is like the bur oak, except that the leaves are 
narrower and the acorns smaller and cylindrical. 
Quercus bicolor (swamp white oak).—A picturesque tree 
which in the open develops an open round-topped crown with 
the upper branches ascending and the lower drooping. Lo- 
cally, the maximum height is 60-70 feet and the trunk diam- 
eter 2-3 feet. This oak may be distinguished by the leaves, 
