F. T. Metzger
American hornbeam (Carpinus caroliniana), also called blue-beech, ironwood, water-beech, or lechillo (Spanish), is a small slow-growing short-lived tree in the understory of eastern mixed hardwood forests. The short, often crooked trunk covered with a smooth slate gray bark is characteristically ridged, resembling the muscles of a flexed arm. The wood is close-grained, very hard, and heavy but little used because such a small tree is rarely converted into sawed products.
General: Birch Family (Betulaceae). American hornbeam is a native, large shrub or small tree with a wide-spreading, flat-topped crown, the stems slender, dark brown, hairy; bark gray, thin, usually smooth, with smooth, longitudinal fluting (resembling a flexed muscle). Its leaves are deciduous, simple, alternate, ovate to elliptic, 3-12 cm long, with doubly-serrate edges, dark green, turning yellow to orange or red in the fall, glabrous above, slightly to moderately pubescent beneath, especially on major veins, with or without conspicuous dark glands. The flowers are unisexual, in catkins, the male (staminate) catkins 2-6 cm long, female (pistillate) catkins 1-2.5 cm long, both types on the same plant (the species monoecious). Fruits are a nutlet 4-6 mm long, subtended by a 3-winged, narrow, leaf-like bract, numerous nutlets held together in pendulous chain-like clusters 2.5-12 cm long, changing from green to brown in September-October. The common name, beam, is an Old English word for tree, with horn suggesting an analogy of the hard, close-grained wood to the tough material of horns.
Variation within the species: the two subspecies are distinguished by morphology and geography. They hybridize or intergrade where their ranges overlap in a broad band running from the Carolinas south to northern Georgia and westward to Missouri, Arkansas, and southeastern Oklahoma. Plants with intermediate features are also found throughout the highlands of Missouri and Arkansas.
1. Leaf blades narrowly ovate to oblong-ovate, 3-8.5(-12) cm long, acute to obtuse at the tip; secondary teeth blunt and small; lower surfaces without small dark glands; southern Atlantic and Gulf of Mexico coastal plains and also extends northward in the Mississippi Embayment. ............. subsp. caroliniana
2. Leaf blades ovate to elliptic, mostly 8-12 cm long, usually abruptly narrowing at the tip, sometimes long and gradually tapered; secondary teeth sharp-tipped, often almost as large as primary teeth; lower surfaces covered with tiny, dark glands; Appalachians and interior forested northeastern North America.
...................... subsp. virginiana (Marsh.) Furlow
Trees of temperate forests in the mountains of Mexico and Central America, formerly considered to be part of Carpinus caroliniana, are now treated as C. tropicalis (J.D. Smith) Lundell spp. tropicalis and C. tropicalis ssp. mexicana Furlow.
Distribution: Widespread in the eastern United States --- from central Maine west to southwestern Quebec, southeastern Ontario, northern Michigan, and northern Minnesota, south to central Iowa and eastern Texas, east to central Florida. Absent from the lowermost Gulf Coastal Plain and the Mississippi embayment south of Missouri).
Ironwood, musclewood, muscle beech, blue beech, water beech
Range and Habitat in Illinois
Regularity: Regularly occurring
Regularity: Regularly occurring
southwestern Quebec, southeastern Ontario, northern Michigan, and
northern Minnesota; south to central Iowa and eastern Texas; and east to
central Florida .
Occurrence in North America
KY LA ME MD MA MI MN MS MO NH
NJ NY NC OH OK PA RI SC TN TX
VT VA WV WI ON PQ MEXICO
-The native range of American hornbeam.
American hornbeam occurs primarily as an understory species in bottomland mixed-hardwood forests. Best sites are in the transition between mesic and wet areas -- near lakes and swamps, on well-drained terraces of rivers, terraces or steep slopes of minor streams with some gradient, coves, ravine bottoms, and rises in lowlands. These sites generally have abundant soil moisture but sufficient drainage to prevent saturation and poor aeration during the growing season, although trees may be abundant on sites flooded for up to about 20% of the growing season. American hornbeam occurs less commonly in upland hardwood forests and may range from 300-900 meters elevation in the Appalachian and Adirondack Mountains. In the northeastern US, it may be an early migrant and form pure stands in moist old fields; it may be a minor seral component of sapling-size tree-shrub communities along the mid-Atlantic coast. Flowering: March-May; fruiting: August-October.
American hornbeam is a native, deciduous small tree. It usually grows
30 to 40 feet (9-12 m) tall [4,13,32,39]. The bark is thin, close, and
usually smooth. The trunk is often crooked, and is usually coarsely
fluted, resembling a flexed muscle [4,7,13]. The fruit is a ribbed
nutlet 0.16 to 0.24 inch (4-6 mm) long [3,4]. It is usually described
as slow-growing and short-lived .
The largest American hornbeam on record for the Southeast was 75 feet
(22.8 m) tall, 21.6 (54.8 cm) d.b.h., and 67.8 inches (172.2 cm) in
Range and Habitat in Illinois
American hornbeam exhibits its best growth on rich, moist soils in
bottomlands, coves, and lower protected slopes. It is also common along
the borders of streams and swamps including bay and river swamps in
Florida [6,8,27], and is also found in hydric hammocks in Florida .
The best sites for American hornbeam are characterized by abundant soil
moisture but sufficient drainage to prevent saturation and poor aeration
during the growing season . American hornbeam is primarily found on
poorly to imperfectly drained sites, although it grows on well-drained
sites also . Hook  rated American hornbeam as only weakly
tolerant of flooding, although it occurs on sites that have a high
probability of flooding in any given year. He commented that mature
trees remain healthy if flooded less than 24 percent of the growing
season, but are most abundant where flooding occurs 10 to 21 percent of
the growing season . In the Adirondack Mountains, American hornbeam
is found on soils derived from limestone, gneiss, shale, and sandstone
. The usual soil pH range for American hornbeam sites is acidic (pH
4.0-5.6), but the tree can be found on soils as high as pH 7.4 .
Maximum elevation for American hornbeam is about 2,900 feet (900 m) in
the southern Appalachians . Its upper elevational range is 3,000
feet (910 m) in the Great Smoky Mountains, but is more common at about
1,600 feet (490 m) . In the Adirondack Mountains, New York,
American hornbeam occurs from 200 to 1,020 feet (60-311 m) elevation .
Key Plant Community Associations
mixed-hardwood forests, but also occurs in dry-mesic upland hardwood
forests . Understory associates of American hornbeam in all parts
of its range include eastern hophornbeam (Ostrya virginiana), flowering
dogwood (Cornus florida), sassafras (Sassafras albidum), witch-hazel
(Hamamelis virginiana), serviceberries (Amelanchier spp.), and speckled
alder (Alnus rugosa). In the northern parts of its range, understory
associates include striped maple (Acer pennsylvanicum), mountain maple
(A. spicatum), red mulberry (Morus rubra), pawpaw (Asimina triloba),
serviceberries, and eastern redbud (Cercis canadensis). Southern
associates include magnolias (Magnolia spp.), deciduous holly (Ilex
decidua), American holly (I. opaca), winged elm (Ulmus alata), sweetbay
(Magnolia virginiana), water-elm (Planera aquatica), parsley hawthorn
(Crataegus marshallii), riverflat hawthorn (C. opaca), common persimmon
(Diospyros virginiana), and Carolina laurelcherry (Prunus caroliniana)
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the terms: hardwood, swamp
24 Hemlock - yellow birch
25 Sugar maple - beech - yellow birch
26 Sugar maple - basswood
27 Sugar maple
28 Black cherry - maple
39 Black ash - American elm - red maple
44 Chestnut oak
52 White oak - black oak - northern red oak
53 White oak
55 Northern red oak
58 Yellow-poplar - eastern hemlock
59 Yellow-poplar - white oak - northern red oak
60 Beech - sugar maple
61 River birch - sycamore
62 Silver maple - American elm
70 Longleaf pine
71 Longleaf pine - scrub oak
73 Southern redcedar
75 Shortleaf pine
76 Shortleaf pine - oak
80 Loblolly pine - shortleaf pine
81 Loblolly pine
82 Loblolly pine - hardwood
83 Longleaf pine - slash pine
87 Sweetgum - yellow-poplar
89 Live oak
91 Swamp chestnut oak - cherrybark oak
92 Sweetgum - willow oak
93 Sugarberry - American elm - green ash
94 Sycamore - sweetgum - American elm
97 Atlantic white-cedar
104 Sweetbay - swamp tupelo - redbay
108 Red maple
110 Black oak
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K098 Northern floodplain forest
K099 Maple - basswood forest
K100 Oak - hickory forest
K101 Elm - ash forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K110 Northeastern oak - pine forest
K111 Oak - hickory - pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
K116 Subtropical pine forest
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES12 Longleaf - slash pine
FRES13 Loblolly - shortleaf pine
FRES14 Oak - pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch
Soils and Topography
Soils primarily associated with the species are in the orders Alfisols, Ultisols, and Inceptisols but American hornbeam also occurs on Entisols, Spodosols, Histosols, and Mollisols.
The best sites may be characterized as having abundant soil moisture but sufficient drainage to prevent saturation and poor aeration of the soil during the growing season (4,51). Typically, the best sites are alluvial or colluvial soils in the transition zone between mesic and wet areas (46), as near lakes and swamps (35), on well-drained terraces of rivers (32,45), terraces or steep slopes of minor streams with some gradient (39), coves, ravine bottoms (33), and rises in lowlands (40). Surface soil layers are somewhat poorly to well drained but the subsoil may not be as well drained, may have a high fluctuating water table, or may be of heavier texture. Soil water-holding capacity usually is high (15,49). Upper soil horizons are primarily loams or of loam-influenced textures. Nutrients and organic matter tend to accumulate on these sites (36), and calcium and magnesium in particular are normally more abundant than in surrounding soils (13). Soil pH tends to be acidic-normally from 4.0 to 5.6-but can be as high as 7.4 (35).
The species also grows well on wetter sites, such as hardwood swamps on mineral soils or mucks (3,37). The key appears to be improving soil moisture conditions through the growing season because the species is only moderately tolerant of flooding (14). It is eliminated from sites inundated more than 25 percent of the time (24). Accordingly, it is absent or rare on the wettest sites, such as lower floodplain terraces, permanently inundated areas, and swamps with peat soils.
American hornbeam also grows, to a lesser extent, on mesic to xeric sites (5,19). In Florida and Ontario the species occurs more often on dry-mesic than on mesic or xeric sites. The dry-mesic sites in Ontario have a higher soil moisture retaining capacity than the others (35). In hilly terrain it is found most frequently on north aspects but also grows on ridge tops and on south aspects where subirrigation of the site improves soil moisture (51).
The upper altitudinal limit of American hornbeam is 910 m (3,000 ft) in the Great Smoky Mountains ' but it is much more common at about 490 in (1,600 ft) (59).
Concentrations of potassium, nitrogen, calcium, and phosphorus in the foliage of the species are low in comparison to those of other species (2). American hornbeam leaf litter, on the other hand, has high concentrations of these nutrients in relation to other species (57).
American hornbeam begins to produce seeds at about 15 years and peaks at 25 to 50 years, probably ceasing at about 75 years. Large seed crops are produced at 3-5-year intervals. Seeds are mainly dispersed by birds. Seed establishment will occur on leaf litter in deep shade. Flooding, drought, damping off, proximity to a conspecific adult, and herbivory are important causes of mortality for first-year seedlings. Reproduction also may occur by sprouts from the root crown and by root sprouts, although the latter apparently is not common.
American hornbeam is best suited to establishment in bottomlands that have already been stabilized by pioneer species. It is shade-tolerant and persists in the understory of late seral and climax communities. Shade tolerance declines with age and American hornbeam is likely to become dominant, with other subcanopy species, at some sites after overstory removal.
Associated Forest Cover
American hombeam is found in a wide variety of forest communities and with many tree species because its habitat frequently is an ecotone in which species from wet and mesic sites intergrade. In the North, it is a minor component of many different types, infrequently becoming the first or second most abundant tree species in the subcanopy layer (32). It is associated with northern hardwoods and their wet site variants. Sugar maple (Acer saccharum) and/or American beech (Fagus grandifolia) are dominant in many situations but may be replaced by eastern hemlock (Tsuga canadensis), yellow birch (Betula alleghaniensis), red maple (Acer rubrum), American elm (Ulmus americana), silver maple (Acer saccharinum), and black ash (Fraxinus nigra) on wetter sites.
In the central portion of its range, American hornbeam also is a minor component of stands. Species dominant in northern stands also dominate here along with white (Quercus alba), black (Q. Velutina), northern red (Q. rubra), scarlet (Q. coccinea), pin (Q. palustris), and chinkapin (Q. muehlenbergii) oak; bitternut hickory (Carya cordiformis); black tupelo (Nyssa sylvatica); sweetgum (Liquidambar styraciflua); yellow-poplar (Liriodendron tulipifera); river birch (Betula nigra); and basswood (Tilia americana).
The species attains its greatest prominence in southern stands, yet remains a member of the understory. In a number of areas it is the most numerous of all tree species in the stand (36,40). It is found in southern mixed hardwood and loblolly pine (Pinus taeda) forests. Overstory species that frequently dominate these stands are sweetgum, water Quercus nigra), white, laurel (Q. laurifolia), willow (Q. phellos), cherrybark (Q. falcata var. pagodifolia), and swamp chestnut (Q. prinus) oak, American beech, black tupelo, red maple, loblolly pine, southern magnolia (Magnolia grandiflora), and yellow-poplar.
The species is also an important member of some nonforest vegetative types in the Northeast. It is an early migrant and forms pure stands in moist old fields (61) and grows in persistent shrub communities in old pastures on hilltops and more exposed hilltops (20).
Understory tree species associated with American hornbeam throughout much of its range include eastern hophornbeam (Ostrya virginiana), flowering dogwood (Cornus florida), witch-hazel (Hamamelis virginiana), the serviceberries (Amelanchier spp.), and speckled alder (Alnus rugosa). Northern associates are striped (Acer pensylvanicum) and mountain maple (A. spicatum). Red mulberry (Morus rubra), pawpaw (Asimina triloba), and eastern redbud (Cercis canadensis) are common associates from the Central States southward. In the South, associated species include sourwood (Oxydendrum arboreum), possumhaw (Ilex decidua), American holly (Ilex opaca), winged elm (Ulmus alata), sweetbay (Magnolia virginiana), water-elm (Planera aquatica), parsley hawthorn (Crataegus marshallii), riverflat hawthorn (C. opaca), common persimmon (Diospyros virginiana), and Carolina laurelcherry (Prunus caroliniana).
Shrub species associated with American hornbeam throughout its range include spicebush (Lindera benzoin) and southern arrowwood (Viburnum dentatum). In the northern half of its range, American hombeam is associated with mapleleaf viburnum (Viburnum acerifolium), redberry elder (Sambucus pubens), common winterberry (Ilex verticillata), and alternateleaf dogwood (Cornus alternifolia). In the southern half of its range it is associated with devils-walkingstick (Aralia spinosa), beautyberry (Callicarpa americana), Virginia-willow (Itea virginica), southern bayberry (Myrica cerifera), sweetleaf (Symplocos tinctoria), and tree sparkleberry (Vaccinium arboreum).
Diseases and Parasites
American hornbeam is susceptible to fire. Wildfires severe enough to kill the hardwood component of white oak stands in Rhode Island eliminated American hornbeam (10). Normally, the species made up 6 percent of the understory stems. However, neither a crown fire nor a ground fire affected the status of American hornbeam in the ninth year after burning a loblolly pine stand in North Carolina (42).
Fire Management Considerations
dying trees usually disappear within a decade .
American hornbeam is sometimes present as an undesirable species in
cut-over pine on terrace or terrace-equivalent sites. Burning in late
spring to early winter may be useful for controlling undesirable
hardwoods on these sites, but is effective only during a long dry
period. Fuels are too moist to achieve good fire spread otherwise .
Broad-scale Impacts of Plant Response to Fire
The Research Project Summary Effects of surface fires in a mixed red and
eastern white pine stand in Michigan and the Research paper by Bowles and others 2007 provide information on prescribed fire and postfire response of several plant species,
including American hornbeam, that was not available when this species review was written.
Plant Response to Fire
In northern Alabama, prescribed fires in a 5- to 6-year-old hardwood
stand (established subsequent to clearcutting) resulted in an increase
in the total number of stems per acre 1 to 2 years after fire. Most of
the increase was attributed to multiple sprouting from existing hardwood
stems that were top-killed by the fire. American hornbeam was listed
with a group of "all others" which numbered 171 stems per acre on the
unburned plot. This group of species averaged 168 stems per acre, 26 of
which were American hornbeam, on burned plots that experienced three
different types of fires: (1) plots burned in spring with a strip
headfire; 72 percent of the area moderately burned, 8 percent lightly
burned or unburned, and 20 percent heavily burned, (2) plots burned in
fall by a slow fire uniformly covering the area, and (3) plots burned in
spring with a moderately intense fire over the entire sampling area
In North Carolina, a 35-year-old loblolly pine (Pinus taeda) plantation
experienced a wildfire in 1931. When the stand was observed in 1940,
American hornbeam density and basal area were low but similar on three
types of plots: surface burn, crown burn, and unburned .
Immediate Effect of Fire
American hornbeam is probably either top-killed or killed by most fires.
A wildfire severe enough to kill the hardwood component of a white oak
(Q. alba) stand in Rhode Island eliminated American hornbeam from the
stand. Prior to the fire, American hornbeam comprised 6 percent of the
American hornbeam is not resistant to fire damage due to its thin bark.
It probably sprouts after top-kill by fire. It occurs mostly in
communities that rarely experience fire.
Florida swamp and hammock communities in which American hornbeam occurs
are estimated as having a fire frequency on the order of one or two
fires per century . Also in Florida, American hornbeam is one of a
number of hardwoods invading longleaf pine (Pinus palustris) communities
in the absence of fire. A community sampled 55 years after the last
recorded fire was dominated by swamp chestnut oak (Quercus michauxii),
American hornbeam, live oak (Q. virginiana), water oak, sweetgum,
eastern hophornbeam, Carolina ash (Fraxinus caroliniana), and pignut
hickory (Carya glabra), with a few remaining large longleaf pine in the
More info for the term: climax
Facultative Seral Species
American hornbeam is tolerant of shade [21,27]. It persists in the
understory of late seral and climax communities. Shade tolerance is
greatest in American hornbeam seedlings and declines with age .
Curtis and McIntosh  rated the climax adaptation of American hornbeam
as 8 (10 is the maximum, usually assigned to species such as sugar maple
[Acer saccharum]). American hornbeam responds positively to overstory
removal. On certain southern sites, it is so aggressive that it
prevents larger species from regenerating after logging or natural
disturbance . In minor streambottoms American hornbeam and other
tolerant subcanopy species are likely to capture a site once the main
canopy is removed . In Connecticut, thinned northern red oak-black
oak-scarlet oak (Quercus rubra-Q. velutina-Q. coccinea) plots had a
higher proportion of American hornbeam and eastern hophornbeam than
unthinned plots .
In North Carolina, American hornbeam first appeared in old fields 12 to
18 years after abandonment, and appeared 25 to 40 years after
abandonment on old fields in New Jersey . American hornbeam was
present on 28-, 30-, and 40-year-old old fields in western Tennessee.
It was not present on the 3- and 12-year-old sites .
Hupp  classes American hornbeam with species that do not normally
invade degraded or newly aggrading substrates (in relation to stream
channelization projects) but are tolerant of bottomland conditions and
have seed that is long-lived (up to 2 years) and dispersed by wind or
water. These species are best suited to establish in bottomlands that
have already been stabilized by pioneer species, and occur in
abundance on undisturbed sites or on sites that are in the later
stages of recovery from channelization .
American hornbeam was present in the understory of a mixed hardwood
bottomland forest dominated by water oak (Q. nigra), sweetgum,
cherrybark oak (Q. falcata var. pagodifolia), and loblolly pine (Pinus
taeda). American hornbeam seedlings and saplings dominated the
reproduction layers in this forest .
In Florida, American hornbeam tends to capture gaps early, but is
replaced by slower-growing and longer-lived evergreen species such as
American holly and common sweetleaf (Symplocos tinctoria) .
The minimum seed-bearing age of American hornbeam is 15 years .
Production is greatest at 25 to 50 years and probably ceases at about 75
years . Large seed crops are produced at 3- to 5-year intervals
[27,32]. Seeds are are mainly dispersed by birds, and are wind blown
only a short distance [6,27]. Matlack  estimated the lateral
movement of American hornbeam diaspores (nut plus bracts) in a 6 mile
per hour (10 km/hr) breeze as 64 feet (19.4 m). Seed dormancy may be
broken by stratification. Stratification at 40 degrees Fahrenheit (4
deg C) for 18 weeks, stratification plus gibberellic acid, and
scarification of the seedcoat plus gibberellic acid all improve
germination [6,27]. The optimum natural seedbed for American hornbeam
is continuously moist, rich, loamy soil protected from extreme
atmospheric changes . American hornbeam will also establish on leaf
litter seedbeds in deep shade, even when competition is present .
Germination occurs from April to June in the spring following seed
In eastern Texas, seedling survival for American hornbeam is low the
first year, but increases substantially thereafter. Flooding,
drought, damping off, proximity to a conspecific adult, and herbivory
were important causes of first year mortality. Mortality tends to be
concentrated in short periods associated with particular events
(flooding, for example). Periods of reduced flooding allowed American
hornbeam seedlings to increase in importance .
Regeneration of American hornbeam after a seed-tree harvest in Arkansas
consisted of new seedlings, advance reproduction, stump sprouts, and
root sprouts .
Growth Form (according to Raunkiær Life-form classification)
Reaction to Competition
Ecologists consider American hombeam a member of near-climax to climax communities. In Wisconsin where climax species are assigned a climax adaptation number of 10, American hombeam is rated 7 and 8 on uplands and 8 and 9 on lowlands for the northern and southern parts of the State, respectively (16). Similarly the species is rated 7 in New Jersey (11). It is ranked fifth highest among 79 Central States species on the basis of a multivariate analysis of various species characteristics that favor establishment and growth under climax forest conditions (58).
American hornbeam first appeared in seral communities developing on old fields about 12 to 18 years after the sites were abandoned in North Carolina (41) and about 25 to 40 years after the sites were sapling-sizeabandoned in New Jersey (26). It enters these communities as a minor component when a sapling-size tree-shrub community is dominant. In much older stands in North Carolina it is more abundant. In maturing second-growth hardwood stands in Connecticut, hornbeam had initially been an important species, the most abundant one, in fact, on moist sites. But, over a 50-year period it declined in density, basal area, and ingrowth, eventually becoming a minor component of all stands (53).
In forests managed for commercial timber production, American hornbeam is considered a weed and is discriminated against in stand improvement. Although hornbeam is considered difficult to kill, herbicides have been effective. Mistblowing a mixture of 2,4-D and 2,4,5-T and injecting 2,4-D, Tordon 101, and Tordon 144 have killed 90 percent or more of the tops (43,44). Prescribed burning is used to control the understory hardwoods, including American hornbeam, that become established under southern pines.
Life History and Behavior
American hornbeam flowers from March 20 to May 6 in the Southeast, and
from April to May in the northern parts of its range, usually before the
leaves are fully grown . The fruits ripen from August to October in
the same season [6,27,39].
American hornbeam responds well to various degrees of overstory removal in regeneration harvests. In two hardwood seed-tree harvest areas in southeastern Arkansas, the proportion of American hornbeam in the reproduction increased during the 18 years after cutting (30). Regeneration of the species consisted of advance reproduction, new seedlings, stump sprouts, and root suckers. Sprouts grew from 1.2 to 1.5 m (4 to 5 ft) in the first year. By the 18th year, American hornbeam was becoming subordinate in diameter to sweetgum and the red oaks. The species also responded well to release after clearcutting hemlock-hardwoods in southern New England (34). However, density and basal area stocking of American hornbeam in relation to other species were unaffected after a partial harvest of a pine-hardwood stand in Louisiana (6).
Seed Production and Dissemination
Flowering and Fruiting
Growth and Yield
Molecular Biology and Genetics
ament and the leaves, but in Ohio the two characteristics do not necessarily vary at the same time, resulting in confusion (8).
American hornbeam exhibits clines (from north to south) in several physiological and morphological properties. Fruit weights increase northward (62); the length of cold preconditioning required for bud bursting varies latitudinally (56), and the specific gravity of the wood is higher for trees growing north of latitude 36°N. than for trees growing at latitudes 31° to 36° N. (55).
The species has eight pairs of chromosomes (63).
Barcode data: Carpinus caroliniana
Statistics of barcoding coverage: Carpinus caroliniana
Public Records: 5
Specimens with Barcodes: 6
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.
American hornbeam is usually regarded as a weed tree because of its
small size and poor form [6,27]. In eastern hardwoods, American
hornbeam may increase in dominance on a stand under single tree
selection management . Intensive site preparation is needed to
regenerate intolerant soft hardwoods (eastern cottonwood [Populus
deltoides], sycamore [Platanus occidentalis], sweetgum [Liquidambar
styraciflua], and yellow-poplar [Liriodendron tulipifera]) in the
presence of American hornbeam . American hornbeam initially
dominated a clearcut site but was eventually overtopped by larger
species . American hornbeam may be controlled by 2,4,5-T .
Overstory cover is important for maintenance of American hornbeam.
Cutting practices should leave some canopy trees for shade .
American hornbeam seedlings grown in full sun responded positively to
increased nutrients (applied at levels to mimic the range of values for
agricultural runoff and sewage sludge) .
Insects and diseases are not usually serious problems for American
Cultivars, improved and selected materials (and area of origin)
Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”
Because of its thin bark, American hornbeam is probably either top-killed or completely killed by most fires. It occurs mostly in communities that rarely experience fire. It sprouts after top-kill by fire and repeated fires at a closely spaced interval will quickly eliminate the species. The wood rots very rapidly and dying trees usually disappear naturally within a decade.
Relevance to Humans and Ecosystems
Uses: Fuelwood, Other fuel
Comments: "OTHER FUEL" = CHARCOAL
Other uses and values
collected for food . The leaves of American hornbeam have been used
as an astringent .
Importance to Livestock and Wildlife
grouse, ring-necked pheasant, and northern bobwhite eat small quantities
of the seeds, buds, and catkins. Seeds are consumed by yellow-rumped
warbler . The seeds are also consumed by ducks, but usually only
when acorn production is limited . Seeds, bark, and wood are eaten
by rabbits, beaver, fox squirrel, and eastern gray squirrel.
White-tailed deer browse the twigs and foliage . American hornbeam
has been reported in wild turkey crops from New York and Pennsylvania .
Wood Products Value
very difficult to work and is used only for tool handles, mallets, and
golf club heads [4,6,7].
Reproduction is browsed by white-tailed deer throughout the species range but it is not a preferred food (7,28). The species is heavily used by beaver because it is readily available in typical beaver habitat (38).
The orange and scarlet coloration in the fall make this an attractive ornamental tree. It is not widely used, however, because it is difficult to transplant and does not do well on exposed sites (60).
The wood of American hornbeam is not important in commerce because the tree is too small, but its tough, dense, and close-grained wood is used for tool handles, levers, wedges, and mallets.
The wood of Carpinus is of minor economic importance because of the small size of the trees. It is whitish, extremely hard, and heavy and has been used for making mallet heads, tool handles, levers, and other small, hard, wooden objects. The wood is not subject to cracking or splitting and was used by American pioneers for bowls and dishes.
American hornbeam is planted in landscapes and naturalized areas. It prefers deep, fertile, moist, acidic soil and grows best in partial shade, but will
grow in full sun. Its chief liabilities in cultivation are a relatively slow growth rate and difficulty in transplantation. It is not drought-tolerant.
Seeds, buds, or catkins are eaten by a number of songbirds, ruffed grouse, ring-necked pheasants, bobwhite, turkey, fox, and gray squirrels. Cottontails, beaver, and white-tailed deer eat the leaves, twigs, and larger stems. Beaver heavily uses American hornbeam, because it is readily available in typical beaver habitat.
Carpinus caroliniana (American hornbeam) is a small hardwood tree in the genus Carpinus. American hornbeam is also known as blue-beech, ironwood, and musclewood. It is native to eastern North America, from Minnesota and southern Ontario east to Maine, and south to eastern Texas and northern Florida. It also grows in Canada (southwest Quebec and southeast Ontario).
It is a small tree reaching heights of 10–15 m, rarely 20 m, and often has a fluted and crooked trunk. The bark is smooth and greenish-grey, becoming shallowly fissured in all old trees. The leaves are alternate, 3–12 cm long, with prominent veins giving a distinctive corrugated texture, and a serrated margin. The male and female catkins appear in spring at the same time as the leaves. The fruit is a small 7–8 mm long nut, partially surrounded by a three- to seven-pointed leafy involucre 2–3 cm long; it matures in autumn. The seeds often do not germinate till the spring of the second year after maturating.
There are two subspecies, which intergrade extensively where they meet:
- Carpinus caroliniana subsp. caroliniana. Atlantic coastal plain north to Delaware, and lower Mississippi Valley west to eastern Texas. Leaves mostly smaller, 3–9 cm long, and relatively broader, 3–6 cm broad.
- Carpinus caroliniana subsp. virginiana. Appalachian Mountains and west to Minnesota and south to Arkansas. Leaves mostly larger, 8–12 cm long, and relatively narrower, 3.5–6 cm broad.
It is a shade-loving tree, which prefers moderate soil fertility and moisture. It has a shallow, wide-spreading root system. The wood is heavy and hard, and is used for tool handles, longbows, walking sticks, walking canes and golf clubs. The leaves are eaten by the caterpillars of some Lepidoptera, for example the Io moth (Automeris io).
Common along the borders of streams and swamps, loves a deep moist soil. Varies from shrub to small tree, and ranges throughout the United States east of the Rocky Mountains.
- Bark: On old trees near the base, furrowed. Young trees and branches smooth, dark bluish gray, sometimes furrowed, light and dark gray. Branchlets at first pale green, changing to reddish brown, ultimately dull gray.
- Wood: Light brown, sapwood nearly white; heavy, hard, close-grained, very strong. Used for levers, handles of tools. Sp. gr., 0.7286; weight 45.41 lbs.
- Winter buds: Ovate, acute, chestnut brown, one-eighth of an inch long. Inner scales enlarge when spring growth begins. No terminal bud is formed.
- Leaves: Alternate, two to four inches long, ovate-oblong, rounded, wedge-shaped, or rarely subcordate and often unequal at base, sharply and doubly serrate, acute or acuminate. They come out of the bud pale bronze green and hairy; when full grown they are dull deep green above, paler beneath; feather-veined, midrib and veins very prominent on under side. In autumn bright red, deep scarlet and orange. Petioles short, slender, hairy. Stipules caducous.
- Flowers: April. Monœcious, apetalous, the staminate naked in pendulous aments. The staminate ament buds are axillary and form in the autumn and during the winter resemble leaf-buds, only twice as large; these aments begin to lengthen very early in the spring, when full grown are about one and one-half inches long. The staminate flower is composed of three to twenty stamens crowded on a hairy torus, adnate to the base of a broadly ovate, acute boot-shaped scale, green below the middle, bright red at apex. The pistillate aments are one-half to three-fourths of an inch long with ovate, acute, hairy, green scales and bright scarlet styles.
- Fruit: Clusters of involucres, hanging from the ends of leafy branches. Each involucre slightly incloses a small oval nut. The involucres are short stalked, usually three-lobed, though one lobe is often wanting; halberd-shaped, coarsely serrate on one margin, or entire.
- "The Plant List: A Working List of All Plant Species". Retrieved 1 April 2015.
- Kew World Checklist of Selected Plant Families
- USDA Forest Service. "Silvics of North America, Vol.2 (USDA Forest Service)".
- Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons. pp. 319–322.
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Native Americans used Carpinus caroliniana medicinally to treat flux, navel yellowness, cloudy urine, Italian itch, consumption, diarrhea, and constipation, as an astringent, a tonic, and a wash, and to facilitate childbirth (D. E. Moerman 1986; no subspecies specified).
Names and Taxonomy
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