Carpinus caroliniana (American Hornbeam)

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Carpinus, Genus, caroliniana, Species,

Genus & species

American hornbeam

Betulaceae

Eastern North America (Nova Scotia to Florida, west to Minnesota and eastern Texas)

Deer Resistant

SunFull Sun – Part Shade – Full Shade

WaterMedium

HardinessZones 3–9

Overview

Carpinus caroliniana is a small to medium deciduous tree reaching 20–35 feet (6–10.5 m) tall with a spread of 20–30 feet (6–9 m). The form is typically multi-stemmed or low-branched with a broadly rounded to vase-shaped crown. The trunk and major limbs are smooth, blue-gray, and sinewy, with long fluted ridges resembling flexed muscles beneath the bark — the source of the common name 'musclewood.' The bark holds this smooth character into old age. Leaves are ovate to elliptic, 2–4 inches (5–10 cm) long, with doubly serrate margins and prominent parallel veins; they are smaller than the 2–5 inch (5–13 cm) leaves of C. betulus. Spring color is medium green, sometimes with a reddish tinge on emerging leaves, darkening to dark green in summer. Fall color ranges from yellow to orange to scarlet-red — more variable and often more saturated than the yellow fall color of C. betulus. Foliage is slightly marcescent in winter, though less persistently than C. betulus. Pendulous male catkins and small female catkins open in April. Fruit are small nutlets with three-lobed leafy bracts in pendant clusters. Growth rate is slow at 8–12 inches (20–30 cm) per year. The species tolerates heavy shade and wet soils, occurring naturally as an understory tree. The dense fibrous root system makes the tree difficult to transplant; container-grown stock establishes more readily than field-dug stock.

Native Range

Carpinus caroliniana is native to eastern North America, from Nova Scotia and Minnesota south to Florida and eastern Texas. It occurs as an understory tree in moist mixed hardwood forests, bottomland woodlands, and along streams and river floodplains from lowland to foothill elevations.

Suggested Uses

Used as a small shade tree, understory tree, and naturalized woodland planting at 15–25 foot (4.5–7.5 m) spacing. Shade and wet-soil tolerance suits the species for rain gardens, stream bank stabilization, and low-lying sites. The multi-stemmed form and smooth muscular bark add year-round structural interest. The species functions as a specimen in residential gardens where a smaller tree than C. betulus is needed. Native plant value for wildlife: the fruits feed songbirds. Not used for formal hedging or containers.

How to Identify

Mature size is 20–35 feet (6–10.5 m), smaller than the 40–60 feet (12–18 m) of C. betulus. The trunk is more prominently smooth and sinewy blue-gray than the gray fluted bark of C. betulus, and the form is typically multi-stemmed rather than the pyramidal-to-rounded single-trunk form of the European species. Fall color includes orange and scarlet-red, a wider range than the yellow-only fall of C. betulus. Leaves are 2–4 inches (5–10 cm) long, shorter than the 2–5 inch leaves of C. betulus. Distinguished from Ostrya virginiana (hop hornbeam) by the smooth bark, versus the shaggy bark and hop-like fruit clusters of Ostrya.

Appearance

Size & Dimensions

Height20' - 35'

Width/Spread20' - 30'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~2 weeks

Flowers: April

Spring

Pendulous male catkins 1–2 inches (2.5–5 cm) long and small greenish female catkins open in April with the emerging leaves. Wind-pollinated. Pendant clusters of three-lobed leafy fruit bracts develop through summer and ripen in September–October. The fruits feed songbirds, turkeys, and small mammals.

Detailed Descriptions

Flower Description

Greenish (inconspicuous catkins)

Foliage Description

Medium to dark green; yellow, orange, to scarlet-red fall color

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade SunFull Shade

Requires 2-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.0 (Acidic to neutral)

3579

Soil Types

loam clay

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Plant in moist, well-drained to occasionally wet soil in partial shade to full sun. Tolerance of heavy shade and wet conditions exceeds that of most ornamental trees, reflecting the species' understory and bottomland origins. Soil pH is adaptable from acidic to slightly alkaline. Consistent moisture supports vigorous growth. The slow growth rate means the tree takes 10–15 years to develop mature character. Transplanting from containers rather than balled-and-burlapped stock improves establishment. No serious pest or disease problems. Heat-tolerant across the wide native range.

Pruning

Prune in late winter to early spring. Train to a single trunk or allow the natural multi-stemmed form. Remove crossing or damaged branches. The species tolerates pruning but does not respond to hedging as readily as C. betulus. The rounded canopy needs minimal shaping.

Pruning Schedule

Prune: February–March

winterearly spring