Crooked Run Valley
hackberry (Celtis occidentalis)
CONFIRMATION STATUS: Confirmed.
TAXONOMY: The fully documented scientific name of hackberry is
Celtis occidentalis L. The taxonomy presented here follows that of the
Great Plains Flora Association which designates three varieties of this
species in the Great Plains. Apparently the variation encountered within
the species makes recognition of these varieties difficult. Fully docu-
mented names of the hackberry varieties encountered in the literature are:
1) Celtis occidentalis var. crassifolia (Lam.) Gray 2) Celtis occidentalis
var. pumila (Pursh) A. Gray, and 3) Celtis occidentalis var. canina (Rafl)
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS: Hackberry is a native,
deciduous small to large tree, its size varying in response to habitat. In poor,
dry sites, growth is so stunted that the plant appears as a shrub. This
drought and flood tolerant tree grows up to 82 feet (25m) high with the
larger branches 26 to 33 feet (8-10m) above the ground, although on the
Great Plains and on dryer sites it usually grows to only 25 to 50 feet (7.5-
15m) high with a diameter of 8-24 inches (20-61cm). On the best sites
hackberry may reach 130 feet (40m) with a diameter of 4 feet (1.25m).
The rather thick (1 to 1 1/2 inches (2.5-4cm)), dark brown to grey bark
is deeply furrowed, checkered and warty when older; the younger branches
are mostly pubescent. Hackberry has lateral roots which tend to be medium
deep to shallow. Early growth of hackberry varies greatly within its range.
Height growth may not exceed 1 inch (2.5cm)/year under a heavy
overstory, but when planted in Great Plains shelterbelts, plants average
1.3 feet (40cm)/year during the first 6 years. Maximum age attained by
hackberry is between 150 and 200 years. The simple, alternate leaves are
lance-ovate or deltoid from 2 to 4.5 inches (5-12cm) long and 1.2 to 2.4
inches (3-6cm) wide with a serrate margin. The lower surface of the leaves
is paler and pubescent. This monoecious tree has perfect, unisexual flowers
which appear in the spring as the new leaves emerge. The inconspicuous,
small, green flowers are wind-pollinated. Staminate flowers appear singly
or in clusters of two to three at the base of a short, green branch. Pistillate
flowers appear singly or in pairs. Hackberry fruit is a round drupe with a
thin, sweet, edible pulp enclosing a bony, cream-colored nutlet. The fruit,
which is usually variable in size, form and color is dark orange or red to
dark purple or black in color, and is about 1/4 to 1/3 inch (0.5-1cm) in
diameter on a 2/3 inch (15mm) pedicel. Hackberry produces good seed
crops each year. Hackberry is host to a large number of insects and
diseases, most of which cause no serious damage. Four gall-producing
insects attack this tree, and the entire crown may be defoliated by the
spiny elm caterpillar or the hackberry butterfly caterpillar. The hackberry
engraver beetle attacks mostly dead or dying branches, but has been
reported to attack living sapwood as well, causing the tree to die. A witches'
-broom caused by the mite Eriophyes spp. and a powdery mildew fungus
causes a rosette-like proliferation of the branch tips, but does not cause
serious damage to the tree. Many ecotypes of this variable species are
known to occur. Varieties are distinguished by such morphological
charcteristics as growth form, height, leaf size and margin, and fruit
shape and color.
REGENERATION PROCESSES: Hackberry regenerates primarily
through sexual reproduction. This tree produces good seed crops most
years, with at least some seed produced each year. Although some seed
may be dispersed by water, most is disseminated principally by birds and
small mammals. The fruit, a drupe with sweet, edible pulp, is consumed
by many species of birds and mammals, which then disperse the seeds in
their feces. Some fruit stays on the tree through the winter, but most is
consumed or falls off before spring. This shade tolerant species is a member
of several late seral and climax communities, reproducing even in heavy
shade. Hackberry seedlings become established in existing hardwood
stands, but rarely in old fields, and seedlings and saplings have been
observed growing in heavy shade where seedlings of other overstory
species did not persist. Height growth may only be 1 inch (0.5cm)/ year
under heavy overstory. Some researchers claim that when cut, hackberry
will produce sprouts from the stumps of small trees, but rarely from those
of larger trees, However, there is little other evidence this species' ability to
SITE CHARACTERISTICS: Hackberry is adapted to a variety of
climatic conditions. Average annual precipitation varies from 14 to 60
inches (35.5-155cm), and the average frost-free season is from 120 to
250 days. Hackberry tolerates an annual temperature variation of 140F
(60C) in the Great Plains. However, the northern extension of its range
is limited by late spring frosts which destroy flowers, or by early autumn
frosts which kill the germs of immature fruits. It grows best on moist
valley soils along streambanks and on flood plains but is also commonly
found on slopes and bluffs, on limestone outcrops, on the north side of sand
dunes in western Nebraska, on upland sites in the central Great Plains
under existing oak stands on all aspects, slopes and ridges, on rocky
hillsides in open woodlands, and along the base of canyon walls of the
Arikaree River in Colorado. In the northern Great Plains portion of its
range, where rainfall is insufficient to support upland tree growth,
hackberry is restricted to well developed river valleys, north slopes and
protected ravines, and is absent from the windswept parts of the western
river valleys. Although principally a bottomland tree, sites with a
permanently high water table are unfavorable for hackberry; however,
periodic flooding is not detrimental. This species has been planted
frequently in the west because of its relative drought tolerance/avoidance,
but mesic hackberry is less successful at coping with water stress than bur
and chinkapin oaks (Quercus macrocarpa and Quercus muehlenbergii).
Hackberry is tolerant of a variety of soils, but grows best on moist, rich soils.
Its growth is stunted and scraggly on poor, dry sites . This species seems to
prefer limestone soils.
Hackberry seldom occurs in pure stands, although it is prominent in the
northern phase of the sugarberry (Celtis laevigata) - American elm
(Ulmus americana) - green ash (Fraxinus pennsylvanica) forest cover
type. It also occurs in several upland forest types in association with sugar
maple (Acer rubrum), basswood (Tilia spp.), post oak (Quercus stellata),
black oak (Quercus velutina), bur oak (Quercus macrocarpa), and eastern
redcedar (Juniperus virginiana). In the central Great Plains, hackberry is
reproducing under chinkapin oak and bur oak stands, and is replacing the
oak woodlands as the major overstory dominant.
SUCCESSIONAL STATUS: Hackberry is found in many forest types
ranging from early to late seral, making its successional position difficult to
determine. This tree is intermediate to tolerant in its ability to withstand
shade and seems to require shade for reproduction of its seedlings.
Hackberry also establishes itself on river floodplains of the central Great
Plains under willow (Salix spp.) and eastern cottonwood (Populus deltoides),
and is probably the climax species. This species is also a member of
several late-seral communities.
SEASONAL DEVELOPMENT: Hackberry, a polygamo-monoecious
tree, flowers when the leaves emerge, or shortly after, in early April in the
southern part of its range, and in late May in the northern part. The fruit,
a drupe, ripens from September to October, and remains on the tree
throughout the winter. This deciduous tree drops its leaves in the fall,
generally after the first frost.
GENERAL DISTRIBUTION: Hackberry is widely distributed in the
eastern United States from northwest Minnesota to central Wisconsin
and Michigan into central New York and throughout the southern New
England states. It is found as far south as northern Georgia, Alabama,
northeastern Mississippi and central Arkansas. This species' range
extends west through central Oklahoma, and includes most of Kansas,
Nebraska, South Dakota and eastern North Dakota. Hackberry also
grows along the Arikaree river in eastern Colorado. In Canada hack-
berry is local in the extreme southern reaches of Manitoba, Quebec
and Ontario. The exact southern part of its range is difficult to establish
because of hackberry's similarity to sugarberry (Celtis laevigata).
SKY MEADOWS DISTRIBUTION:
Tree specimens can be found on trails marked in red.
Appalachian Trail/Old Trail
South Ridge/North Ridge
Rolling Meadows/ Lost Mountain
HABITAT TYPES AND PLANT COMMUNITIES: Hackberry is a
documented member of two plant communities in the western extension
of its range. It is listed as an associated species of the green ash (Fraxinus
pennsylvanica)-western snowberry (Symphoricarpos occidentalis) plant
communities in Nebraska and in the Black Hills National Forest of South
Dakota, and in the plains cottonwood (Populus sargentii)/western
snowberry plant communities in central Montana, southwestern North
Dakota, southcentral South Dakota and Thunder Basin National Grassland
of Wyoming. No published classification schemes were encountered for the
eastern extension of hackberry's range.
IMPORTANCE AND USES: The fruit of hackberry, a sweet, edible
drupe, is eaten by many small birds and mammmals. These berries persist
though the winter, but most are consumed or fall off by the spring. Over
25 species of birds feed on hackberries, including: wild turkey, ring-necked
pheasant, quail, prairie sharp-tailed grouse, lesser prairie chicken, cedar
waxwing, yellow-bellied sapsucker, mockingbird, robin, bobwhite and
others. The fox squirrel will feed on both the fruit and the nipple galls.
Deer will browse on the leaves of hackberry, but generally elk, deer and
antelope do not prefer hackberry over other browse species.
This tree is not poisonous to livestock, but with poor palatability and
poor protein value, it is not considered to be a preferred species.
Hackberry, as a member of several riparian and wooded draw communities,
provides valuable cover for wildlife and livestock, especially in the plains
regions where quality cover is often lacking.
Although hackberry thrives better on fertile soils than on poor ones, its
ability to grow on sterile soil is one of its best qualities. This tree will live
and bear seed in situations where almost any other tree would die. In
more humid regions it grows on dry, sometimes barren soil, and on the
semiarid Plains, it thrives best along water courses. This species seems
to favor limestone soils. Due to these characteristics, especially its ability
to withstand drought, and its growth in a wide variety of sites and soils,
this species may be of some value in reclamation of disturbed sites.
Hackberry wood is of medium hardness and strength, white to yellowish
in color and rather elastic; its specific gravity is 0.49. This wood makes
excellent fuel, almost equaling hickory, and is used also in the manufacture
of cheap furniture. The technical qualities of hackberry wood resemble
those of elm (Ulmus spp.) and white ash (Fraxinus americana), and it is
sometimes used as a substitute for these species. Hackberry is not a
commercially important tree (except as firewood) with its low timber
value, but when peeled and properly seasoned hackberry poles serve
many useful purposes. However, the wood is not durable when in contact
with the soil.
Hackberry, first cultivated in 1656, has no showy flowers or colorful fall
foilage, and is therefore not often selected for ornamental planting, although
it is an excellent shade tree, rivaling American elm (Ulmus americana).
However, it is widely planted in windbreaks and landscaping, mostly
because of its ability to tolerate drought. Apparently a coarse thread
suitable for ropes and matting is obtained when the bark is steeped in
water until the fibers separate. Also, the berries and seeds of hackberry
are eaten by many species of birds, making this species useful for increasing
habitat and natural food supplies for birds frequenting residential areas.