Identifying characteristics:
The bitternut hickory grows to 75 feet tall with a straight trunk and an
open, rounded, narrow crown that spreads at the top with age. It is short-lived
for a hickory (to 200 years). The pinnately-compound leaves
are alternate and 6 to 10 inches long, with 7 (sometimes 5 or 9) sharply
serrate leaflets. The terminal leaflet is 3 to 6 inches long, the laterals
smaller. Leaflets are bright green and hairless above and paler and hairy
on the midrib and veins below. The lower surface is often gland-dotted.
Fall color is a bright, clear yellow. Flowers
appear in spring when the leaves are nearly fully grown. Male flowers occur
in slender, stalked, slightly hairy, branched catkins; female flowers occur
in short spikes. The nut is an
inch in diameter, produced inside a thin, hairy husk that is 4-winged above
the middle. The husk turns from yellow-green to brown, splitting halfway
open at maturity. The semicircular to heart-shaped leaf scars are
relatively large, with numerous bundle scars. Buds are enclosed in
two bright yellow bud scales that meet but do not overlap along the edges.
Bark is close and firm, and remains
smooth and gray for many years, eventually becoming shallowly furrowed with
low, reddish-brown, interconnecting ridges. Shaggy bark does not develop
in this species.
Similar species:
- shagbark hickory (C. ovata)
- blue ash (F. quadrangulata )
- green ash (F. pennsylvanica)
- white ash (F. americana)
Ecology:
Distribution: This is probably the most uniformly distributed
and abundant hickory in North America. It ranges further north than any
other hickory species and is native from Quebec to Minnesota, south to Florida
and Louisiana. It is native to Iowa and is the only native hickory in most
of the northwestern part of the state.
Habitat: Although this hickory prefers moist, well-drained soils, it is found in a variety of sites, including areas subject to flooding and on rich soils of drier, sheltered slopes. The young trees are shade tolerant and this species is a common understory tree across most of Iowa. Canker diseases occasionally create rough, rounded swellings on trunks of saplings, and anthracnose sometimes causes defoiation. A number of insect pests attack hickories, including hickory leaf stem gall aphid, hickory bark beetle and painted hickory borer.
Uses:
Wood: Although not quite as hard or heavy as the wood of the shagbark
hickory, bitternut wood is close-grained, tough and shock-resistant.
It is used for tool handles, charcoal and meat smoking. Good quality logs
are used for paneling and veneer, but poorer wood is used for pallets, lumber
and pulp. Settlers used the oil from the nuts to light their lamps and for
treating rheumatism.
Wildlife: The nuts are bitter and unpalatable, and are not eaten by humans and wildlife prefer nuts of other hickories. The tree relies on flooding and gravity to disperse the seeds.
Horticulture: This tree grows faster and has more spectacular fall foliage than other hickory species. It is not often used in landscaping as it is difficult to transplant, slow to establish and there are many other faster-growing native trees available. Mature trees are handsome specimens and should be preserved on development sites.
