26 MISSOURI BOTANICAL GARDEN BULLETIN 
of its durability, strength, and toughness. It is also exten- 
sively used in the manufacture of furniture and carriages, 
being especially adapted to high-grade work, also in cooper- 
age. The bark is rich in tannin and is used for the tanning 
of leather. The bark of some of the European species pro- 
duces the cork of commerce. The galls which are caused by 
the stings of insects are also rich in tannin and have been 
used in the manufacture of writing ink. 
Oaks are extremely valuable as ornamentals in landscape 
work, being regarded by many as the most varied and the 
most beautiful and picturesque of all deciduous trees. They 
are not easily transplanted from their native locations in the 
woods, owing to the formation of a tap-root very early in 
life, but if properly handled in the nursery, with early re- 
moval of the tap-root and frequent transplanting to prevent 
the formation of a new tap-root before being planted in their 
permanent place, most of them can be moved with ease. Oaks 
are not well adapted to the smoky atmosphere of cities. 
The genus Quercus which consists almost entirely of large 
trees comprises about three-hundred species throughout the 
world. About fifty of these are native to America, half of 
them distributed in the eastern states and half on the western 
slopes. No Pacific-coast species are found naturally in the 
eastern states and no eastern species across the Rocky Moun- 
tains. 
Our local oaks may be classified into two general groups: 
1. THE WHITE-OAK GROUP 
Acorns ripening in one season; lobes of leaves rounded ; 
bark pale and often scaly. 
Quercus alba (white oak).—The white oak is the most val- 
uable of our local oaks, though rather slow in growth. Locally 
it attains a height of about 100 feet with a trunk diameter of 
about 6 feet. When grown in the open it generally divides 
near the ground in a great many lateral branches, forming 
a wide irregular crown. It grows in any ordinary good soil 
regardless of exposure. It is easily distinguished from other 
local oaks by its grayish white bark which is broken up into 
loose scales, and by‘its leaves, which are round-lobed, smooth 
