Summer Key to the Common Trees of Durham County, North Carolina

by Will Cook,

Main Key

1. Leaves needle-like or scale-like, Gymnosperm
   2. Leaves scale-like – Juniperus virginiana
   2. Leaves needle-like, in bundles – Pinus
1. Leaves broader, flat, Angiosperm
   3. Leaves opposite
      4. Leaves compound
         5. Leaves palmately compound - Aesculus sylvatica
         5. Leaves pinnately compound
            6. Young twigs green, leaflets lobed – Acer negundo
            6. Young twigs otherwise, leaflets unlobed – Fraxinus
      4. Leaves simple
         7. Leaves entire
            8. Veins of leaves curving inward, parallel to leaf edge, leaves medium-sized and pointed – Cornus florida
            8. Veins otherwise, leaves large and blunt-tipped - Chionanthus virginicus
         7. Leaves lobed and toothed – Acer
         7. Leaves toothed but not lobed – Viburnum
         7. Leaves toothed and may be lobed, huge (30-50 cm long), densely
            tomentose (hairy) on all surfaces, and sticky – Paulownia tomentosa
   3. Leaves alternate
      9. Leaves compound
         10. Leaves once-compound
            11. Very weak large shrub or small tree with horizontally elongated lenticels in the bark – Rhus
            11. Tree, not armed with thorns
               12. Leaves with 5-9 leaflets, fruit husk dehiscent – Carya
               12. Leaves with 11-19 leaflets, fruit husk indehiscent – Juglans nigra
               12. Leaves with 15-27 leaflets, very malodorous – Ailanthus altissima
            11. Tree, armed with thorns – Robinia pseudoacacia
         10. Leaves twice-compound – Albizia julibrissin
      9. Leaves simple
            13. Leaves entire, not toothed or lobed
               14. Leaves large, 6-24 inches long, 3-6 inches wide, and tapered at both ends – Magnolia
                  15. Leaves thick, coriaceous, lustrous, evergreen – Magnolia grandiflora
                  15. Leaves thin, over 12 inches long, arranged in clusters - Magnolia tripetala
                  15. Leaves thin, under 12 inches long, not clustered, malodorous when crushed - Asimina triloba
               14. Leaves bristle-tipped, fruit an acorn – Quercus
               14. Leaves cordate (heart-shaped) – Cercis canadensis
               14. Leaves otherwise
                  16. Leaves slightly glaucous beneath, leaf-scars with 1 bundle scar, ovary superior,
                     fruit a large (to 4 cm) subglobose berry – Diospyros virginiana
                  16. Leaves green beneath, sometimes with a few remote teeth, leaf-scars with 3 bundle scars,
                     ovary inferior, fruit a small drupe – Nyssa sylvatica
            13. Leaves toothed or lobed
               17. Leaves thick, coriaceous, and evergreen – Ilex
               17. Leaves densely white tomentose below, shiny green above, maple-shaped (with 5 acute lobes) – Populus alba
               17. Leaves otherwise – see key B below

Key B –  trees with alternate, simple, toothed or lobed, deciduous leaves

1. Leaves lobed, but not toothed
   2. Leaves aromatic, notched at top, 4-lobed – Liriodendron tulipifera
   2. Leaves aromatic, variable in shape, with 0-2 lobes – Sassafras albidum
   2. Leaves otherwise – Quercus
1. Leaves both lobed and toothed
   3. Leaves star-shaped (5-pointed), aromatic, fruit a star-shaped ball – Liquidambar styraciflua
   3. Leaves otherwise
      4. Petiole bases swollen and covering the buds, fruits ball-shaped,
         outer bark exfoliating to reveal white inner bark – Platanus occidentalis
      4. Leaves otherwise
         5. Branches with long, slender thorns – Crataegus
         5. Branches otherwise
            6. Petioles exuding milky sap when broken – Morus
            6. Petioles not exuding milky sap – Quercus
1. Leaves toothed, but not lobed
   7. Branches with long, slender thorns – Crataegus
   7. Branches without thorns
      8. Leaves spicy-aromatic, with yellow resin-dots beneath – Morella cerifera
      8. Leaves otherwise
         9. Bark of young trunks and branches with horizontally-elongated lenticels
            10. Twigs and leaves with cherry-like odor – Prunus serotina
            10. Leaves odorless, old bark peels off in sheets, – Betula nigra
         9. Bark and twigs otherwise
            11. Petioles exuding milky sap when broken – Morus
            11. Petioles not exuding milky sap
               12. Leaves narrowly lanceolate – Salix nigra
               12. Leaves broader, less than 4x as long as wide
                  13. Leaf margins with large teeth
                     14. Leaves ovate, buds long and tapered, sharply pointed – Fagus grandifolia
                     14. Leaves otherwise – Quercus
                  13. Leaf margins with small, fine teeth
                     15. Leaves with simple teeth
                        16. Leaves usually arranged in clusters on short spur branches, small tree or large shrub - Ilex
                        16. Leaves uneven at base, broadest at base, with 3 prominent veins, large tree – Celtis laevigata
                        16. Leaves symmetrical at base, lanceolate, medium-sized tree – Oxydendrum arboreum
                     15. Leaves doubly toothed
                        17. Leaves uneven at base – Ulmus
                        17. Leaves symmetrical or nearly so at base
                           18. Bark smooth, muscular; lateral veins of leaves extending into the marginal teeth;
                              fruits enveloped by the base of leaf-like bracts – Carpinus caroliniana
                           18. Bark scaly; lateral veins branching within the margin of the leaf;
                              fruits enclosed in bracts arranged in hop-like clusters – Ostrya virginiana


Juniperus virginiana – Eastern Redcedar – Cupressaceae. Common small to medium-sized tree of old fields and other open areas

Pinus – Pine – Pinaceae

1. Leaves mostly 2 per fascicle
   2. Leaves twisted, less than 6 cm long – Pinus virginiana
   2. Leaves not twisted, 7-13 cm long – Pinus echinata
1. Leaves mostly 3-4 per fascicle, 15-20 cm long – Pinus taeda

Pinus echinata – Shortleaf Pine.  Most common on drier sites.
Pinus taeda – Loblolly Pine.  The most abundant tree in the eastern Piedmont and Coastal Plain, especially on mesic and moist sites.
Pinus virginiana – Virginia Pine.  Common on poor soil.  More common further north and west.


Acer – Maple – Aceraceae

1. Leaves compound – Acer negundo
1. Leaves simple
   2. Leaf sinuses sharply pointed – Acer rubrum
   2. Leaf sinuses rounded – Acer floridanum

Acer floridanum – Southern Sugar Maple.  Fairly common in rich woods.
Acer negundo – Boxelder.  Common along streambanks and in wet areas.
Acer rubrum – Red Maple.  One of our most abundant tree species.
1. Mature leaves densely hairy beneath - A. rubrum var. drummondii - rare(?) tree of swamps
1. Mature leaves smooth or nearly so beneath (young leaves often hairy)
   2. Leaves normally with five sharply-pointed lobes - A. rubrum var. rubrum - most abundant, occuring in a variety of habitats
   2. Leaves normally with three bluntly-pointed lobes - A. rubrum var. trilobum - common in swamps and bottomlands

Aesculus sylvatica - Painted Buckeye - Hippocastanaceae/Sapotaceae. Fairly common understory large shrub or small tree of rich bottomland forests.

Ailanthus altissima – Tree-of-Heaven – Simaroubaceae.  Weedy tree introduced from China.  Common along roadsides.

Albizia julibrissin – Mimosa – Mimosaceae/Fabaceae (Leguminosae).  Another weedy tree introduced from China. Common in disturbed areas, roadsides, and edges of forests.

Asimina triloba - Pawpaw - Annonaceae. Fairly common small tree of bottomland forests.

Betula nigra – River Birch – Betulaceae.  Common along river banks.

Carpinus caroliniana – Ironwood, American Hornbeam – Betulaceae.  Common small tree along streambanks and in moist woods with distinctive smooth muscular bark.
1. Leaves with an acute apex, smaller and blunter secondary teeth, and lacking dark glands on the underside; bracts of the infructescence more rounded and with a few blunt - C. caroliniana ssp. caroliniana
1. Leaves with an abruptly narrowed or acuminate apex, larger and sharper secondary teeth, and dark glands on the underside; bracts of the infructescence sharper with more, sharper teeth - C. caroliniana ssp. virginiana

Carya – Hickory – Juglandaceae

1. Buds yellow; bud scales valvate (with two non-overlapping scales); bud scale scars wide, separate – Carya cordiformis
1. Buds not yellow; bud scales imbricate (many overlapping scales); bud scale scars in a distinct ring
   2. Bark shaggy; margins of young leaflets densely ciliate; older leaflet teeth with persistent tufts of trichomes
      3. Young twigs thick, not blackish on drying – Carya ovata
      3. Young twigs thin, blackish on drying – Carya carolinae-septentrionalis
   2. Bark not shaggy; leaflets otherwise.
      4. Twigs stout, terminal buds 8-20 mm long, leaves densely hairy – C. tomentosa
      4. Twigs slender, terminal buds 3-15 mm long, leaves mostly glabrous
         5. Leaves with 5 leaflets, glabrous – Carya glabra
         5. Leaves with 5-7 leaflets, pubescent on veins beneath – C. ovalis

Carya carolinae-septentrionalis – Carolina Shagbark Hickory.  Uncommon, found in uplands.
Carya cordiformis – Bitternut Hickory.  Fairly common in bottomlands.
Carya glabra – Pignut Hickory.  Common in uplands.
Carya ovalis – Red Hickory.  Occasional.
Carya ovata – Shagbark Hickory. Fairly common, most often found in bottomlands.Carya tomentosa - Mockernut Hickory. Our most common hickory.

Celtis laevigata – Sugarberry – Ulmaceae/Celtidaceae.  Large tree common in moist bottomlands with interesting warty bark.

Cercis canadensis – Eastern Redbud – Fabaceae (Leguminosae) or Caesalpiniaceae.  Common small tree.

Chionanthus virginicus - Fringetree - Oleaceae. Fairly common understory small tree or large shrub.

Cornus florida – Flowering Dogwood – Cornaceae.  Common understory tree.

Crataegus – Hawthorn – Rosaceae. Uncommon small thorny trees, the species can intergrade.
Crataegus crus-galli - Cockspur Hawthorn
Crataegus flabellata - Fanleaf Hawthorn
Crataegus marshallii - Parsley Hawthorn
Crataegus phaenopyrum - Washington Hawthorn
Crataegus uniflora - Oneflower Hawthorn
Crataegus viridis - Green Hawthorn

Diospyros virginiana – Persimmon – Ebenaceae.  Common.

Fagus grandifolia – American Beech – Fagaceae.  Common in rich, mesic woods.

Fraxinus – Ash – Oleaceae

1. Leaflets whitish beneath, leaf scars U-shaped, surrounding buds – Fraxinus americana
1. Leaflets greenish beneath, leaf scars not surrounding lateral buds – Fraxinus pennsylvanica

Fraxinus americana – White Ash. Fairly common.
Fraxinus pensylvanica – Green Ash. Fairly common in bottomlands and swamps.

Ilex – Holly – Aquifoliaceae

1. Leaves with prickles – Ilex opaca
1. Leaves without prickles
   2. Leaves small, leathery, evergreen – Ilex vomitoria
   2. Leaves thin, deciduous
      3. Leaves small, bluntly toothed, widest above the middle - Ilex decidua
      3. Leaves medium-sized, sharply toothed, widest below the middle - Ilex montana

Ilex decidua - Possumhaw, Deciduous Holly. Fairly common small understory tree.
Ilex montana - Mountain Winterberry. Uncommon small understory tree.
Ilex opaca – American Holly.  Common understory tree.
Ilex vomitoria – Yaupon.  Commonly planted on campus, such as in front of Bio Sci.  This coastal plain native is a fairly common escape.  Leaves contain caffeine and may be used to make a tea.

Juglans nigra – Black Walnut – Juglandaceae.  Uncommon large tree of bottomland forests.

Liquidambar styraciflua – Sweetgum – Altingiaceae (Hamamelidaceae).  Abundant early-successional tree.

Liriodendron tulipifera – Tulip-Poplar – Magnoliaceae.  Common early-successional tree.

Magnolia - Magnolia - Magnoliaceae

1. Leaves thick, dark green and glossy above, evergreen - M. grandiflora
1. Leaves thin, light green, deciduous - M. tripetala

Magnolia grandiflora – Southern Magnolia.  Abundant on campus; fairly common escape. Native to the southernmost coast of N.C. and south
Magnolia tripetala - Umbrellatree. Uncommon native understory tree.

Morus – Mulberry – Moraceae

1. Leaves shiny above, slightly scabrous – Morus alba
1. Leaves dull above, very scabrous – Morus rubra

Morus alba – White Mulberry.  Uncommon weedy small tree on campus, native to Asia.
Morus rubra – Red Mulberry.  Uncommon small forest understory tree.

Morella cerifera – Wax Myrtle – Myricaceae.  Commonly planted, uncommon in the wild here on the western edge of its native range. (= Myrica cerifera)

Nyssa sylvatica – Blackgum, Black Tupelo – Nyssaceae.  Common.

Ostrya virginiana – Hophornbeam – Betulaceae.  Uncommon small tree.

Oxydendrum arboreum – Sourwood – Ericaceae.  Common understory tree in drier forests. Never grows straight.

Paulownia tomentosa – Princesstree – Scrophulariaceae. Weedy tree introduced from China.

Platanus occidentalis – American Sycamore – Platanaceae.  Common large tree along rivers.

Populus alba – White Poplar – Salicaceae.  Introduced from Europe. Usually forms many suckers.

Prunus serotina – Black Cherry – Rosaceae

Quercus – Oak – Fagaceae. Note: hybrids are not rare.

1. Leaves not toothed or lobed
   2. Leaves lanceolate, deciduous – Quercus phellos
   2. Leaves oblanceolate, obovate, or elliptic; evergreen – Quercus hemisphaerica
1. Leaves toothed or lobed
   3. Leaves, leaf lobes, or teeth not bristle-tipped
      4. Leaves deeply lobed
         5. Leaf lobes 7 or more, lower surfaces glabrous – Quercus alba
         5. Leaf lobes fewer, leaves cross-shaped, pubescent below – Q. stellata
      4. Leaves shallowly lobed
         6. Tree of xeric uplands, bark dark gray, tight, deeply furrowed – Q. montana
         6. Tree of wet bottomlands, bark pale gray, loose, breaking into plates or scales – Quercus michauxii
   3. Leaves, leaf lobes, or teeth bristle-tipped
      7. Leaves shallowly 3-lobed near the broad apex
         8. Leaves 5-10 cm long, glabrous below except for tufts of hairs in the vein axils – Quercus nigra
         8. Leaves 10-30 cm long, pubescent beneath
            9. Petioles short and stout, 0.5-1.5 cm long – Q. marilandica
            9. Petioles long and slender 2-5 cm long – Q. falcata
      7. Leaves shallowly to deeply 5-12-lobed
         10. Mature leaves pubescent beneath, with stellate hairs
            11. Mature leaves loosely and coarsely pubescent, the pubescence easily rubbed off – Q. velutina
            11. Mature leaves densely, finely, and permanently pubescent
               12. Terminal lobe of leaves usually long-attenuate, narrow, and curved to one side (falcate);
               leaves with 3-7 irregular lobes; tree of dry uplands – Q. falcata
               12. Terminal lobe of leaves usually short, broadly triangular, not curved;
               leaves with 5-9 uniform lobes; tree of moist bottomlands – Q. pagoda
         10. Mature leaves glabrous beneath, except for hairs in the main vein axils
            13. Leaves relatively shallowly lobed, the sinuses extending less than 2/3 of the way to midrib, upper leaf surface dull – Q. rubra
            13. Leaves deeply lobed, the sinuses extending 2/3 to 9/10 of way to midrib, upper leaf surface lustrous
               14. Tree of xeric upland forests, acorn cup turbinate, covering 1/2 of acorn – Q. coccinea
               14. Tree of moist bottomland forests, acorn cup nearly flat at base, covering 1/4 to 1/3 of acorn – Q. shumardii

Quercus alba – White Oak.  One of our most common trees.
Quercus coccinea – Scarlet Oak. Common in xeric uplands.  Brilliant scarlet foliage in fall.
Quercus falcata – Southern Red Oak.  Common in upland forests
Quercus hemisphaerica – Darlington Oak.  Common street tree, not naturalized. Native to the coastal plain.
Quercus marilandica – Blackjack Oak.  Fairly common on poor, dry soils.
Quercus michauxii – Swamp Chestnut Oak. Common in moist bottomland forests.
Quercus prinus – Chestnut Oak.  Common in xeric uplands.  (= Q. prinus)
Quercus nigra – Water Oak.  Found in moist bottomland forests.
Quercus pagoda – Cherrybark Oak.  Common in moist bottomland forests.
Quercus phellos – Willow Oak.  Most common large tree planted along streets and on campus.  Common in moist bottomland forests.
Quercus rubra – Northern Red Oak.  Common.
Quercus shumardii – Shumard Oak.  Fairly common in moist bottomland forests.
Quercus stellata – Post Oak. Common in upland forests.
Quercus velutina – Black Oak. Common in upland forests.

Rhus – Sumac – Anacardiaceae

1. Leaf rachis winged, leaflets entire or nearly so – Rhus copallinum
1. Leaf rachis not winged, leaflets evenly serrate – Rhus glabra

Rhus copallinum – Winged Sumac, Shining Sumac.   Large shrub or small tree, especially common along roadsides.
Rhus glabra – Smooth Sumac. Large shrub or small tree, especially common along roadsides.

Robinia pseudoacacia – Black Locust – Fabaceae (Leguminosae).  Fairly common in disturbed areas.  Introduced from the Appalachian mountains.

Salix nigra – Black Willow – Salicaceae.  Common along rivers and streams.

Sassafras albidum – Sassafras – Lauraceae. Fairly common small tree.

Ulmus – Elm – Ulmaceae

1. Leaves mostly less than 7 cm long, young twigs usually with corky wings – Ulmus alata
1. Leaves mostly more than 7 cm long, without corky wings, usually very uneven at base
   2. Leaf upper surfaces scabrous – Ulmus rubra
   2. Leaf upper surfaces glabrous – Ulmus americana

Ulmus alata – Winged Elm.  Very common, especially in disturbed areas.
Ulmus americana – American Elm.  Fairly common in bottomland forests.
Ulmus rubra – Slippery Elm.  Fairly common.

Viburnum - Blackhaw – Adoxaceae/Caprifoliaceae

1. Petioles, leaf undersides, and terminal buds with rusty hairs, uppersides of leaf lustrous - V. rufidulum
1. Petioles, leaf undersides, and terminal buds without rusty hairs, uppersides dull - V. prunifolium

Viburnum prunifolium – Blackhaw.  Fairly common small tree.
Viburnum rufidulum - Rusty Blackhaw. Uncommon small tree.

Keys adapted from:

Grimm, WC. 1962. How to Recognize Trees. New York: Stackpole Books.
Radford, AE, HE Ahles, and CR Bell. 1968. Manual of the Vascular Flora of the Carolinas. Chapel Hill: The University of North Carolina Press.
Weakley, AS. In prep. Flora of the Carolinas and Virginia.

Durham County NC trees, shrubs, and woody vines

North Carolina trees, shrubs, and woody vines

Created 6/30/1999, last revised 1/9/2011

All photographs and text ©2011 by Will Cook unless otherwise indicated.