Identifying characteristics:
The pin oak has a broad, pyramidal crown, with a tall, tapering, usually
unforked trunk. The slender lateral branches grow upwards on the topmost
portion of the tree, grow out horizontally in the middle portion, and sweep
downward, often to the ground, in the lower portion. This tree can grow
to 100 feet tall, but in cultivation is usually 50 to 80 feet high. The
common name derives from the small, stiff, spur-like branchlets that project
out like "pins" from the trunk and larger branches. The 3- to
6-inch-long leaves are simple, alternate,
and have 5 to 7 bristle-tipped lobes and U-shaped sinuses (spaces between
the lobes). Midveins of the lower lobes curve conspicuously backwards. The
upper surface is glossy and dark green, the lower surface paler with tufts
of hairs in the vein axils. Fall color is variable from russet to bronze
and brilliant red. This is one of the first oaks to bloom in spring. Male
and female flowers are produced on
the same tree in separate catkins, on the current year's growth, as the
leaves unfold. Male flowers are produced in drooping, hairy catkins and
the tiny female flowers are produced singly or in clusters of 2 to 4 on
a short stalk. The almost stalkless (sessile) acorns
are solitary or clustered 2 or 3 at the ends of the previous season's growth.
They are almost rounded, reddish-brown, often striped and are 0.5 inches
long. A saucer-shaped cup with thin appressed scales covers only the base
of the nut. The ovoid buds taper to a pointed tip and are covered
with light reddish-brown scales, sometimes with fine hairs along the margins.
The bark is smooth and grayish-brown
when young, becoming shallowly fissured with low, flat, scaly ridges.
Similar species:
- scarlet oak (Q. coccinea)
- black oak (Q. velutina)
- northern red oak (Q. rubra)
- Hill's oak (Q. ellipsoidalis)
Ecology:
Distribution: The pin oak is native from New York to Kansas, south
to Arkansas and Tennessee. It is found along the Mississippi River
and its lower tributaries in southeastern Iowa and is planted throughout
the state.
Habitat: The pin oak is usually found on floodplains and along stream banks, where water may stand for several weeks in early spring. It also, however, flourishes on deep, well-drained loamy soils of upland flats. It is a fast grower, is hardy from zone 4 to 8 and requires full sun. Alkaline soils (above 7.5 pH) can cause iron and manganese chlorosis that can lead to decline and death of affected trees. The pin oak is subject to oak wilt, and galls can be a problem.
Uses:
Wood: The light brown wood is hard, heavy, coarse-grained,
and strong (but not as strong as red oak). It is occasionally used for general
construction and as posts, but the wood is often too knotty for use as lumber
due to the numerous lateral branches. The wood is good for firewood and
the bark is used as a yellow dye, for tanning and as a medicinal astringent.
Wildlife: The acorns, which are often available near water, are eaten by wood ducks and mallards. White-tail deer, turkeys, quail, squirrels and small rodents also feed on the acorns. The leaves persist into winter and offer winter cover for many wildlife species.
Horticulture: The pin oak is an excellent shade tree and perhaps the most popular native oak used for landscaping in Iowa. It has shallow, fibrous roots that make it easy to transplant; handsome, glossy summer foliage; and an attractive pyramidal shape. It is ideal for larger spaces in parks, golf courses and commercial landscape settings. 'Crown Right' has a more upright habit with branches at a 30- to 60-degree angle that do not reach the ground
