Purdue Biological Sciences: Ross Biological Reserve: Trees

Field Key to Major Trees

Some leaf characteristics can vary depending on environmental conditions (light, temperature) and condition of the tree. Bark, bud, twig, fruit, and flower characteristics can also be diagnostic, but leaves are a good place to start. Many good guides exist, including those from which these drawings were taken:

Trees of North America, CF Brockman & R Merrilees, Golden Press

Eastern Trees, GA Petrides & J Wehr, Houghton Mifflin

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Important Leaf Characteristics

  • Arrangement on Twig:
  • Dissection:
    • Simple (no leaflets)
    • Compound
      • Pinnately
      • Palmately
  • Shape:
    • Broad or narrow
    • Symmetry
  • Margins:
    • Toothed or smooth
    • Lobed
  • Venation:
    • Texture
    • Pattern
  • Texture:
    • Thin or leathery
    • Smooth or hairy

 

Leaves opposite or in whorls

Leaves opposite, or in whorls

Leaves (not leaflets) alternate

Alternate leaves

Simple Leaves, Untoothed (in shape categories)

Simple Shapes:

CC: Redbud (Cercis canadensis): heart-shaped, dark thin rough bark (purple flowers in spring)

Eastern redbud leaves

 

TA: Basswood (Tilia Americana): heart-shaped but toothed; lightly ridged bark, oval clumped trunks

American Basswood leaves and branches

 CF: Flowering Dogwood (Cornus florida): oblong, veins become parallel to edge; med. brown flaky bark

Flowering dogwood, with fruit, and winter twig with flower buds

 

SA: Sassafras (Sassafras albidum): 1-3 rounded lobes ("mittens"); fragrant cinnamon brown twigs

Sassafras leaves, with staminate flowers and pistillate flower

 

Palmately lobed:

AS: Sugar maple (Acer saccharum): pointed lobes; mostly smooth gray bark

Sugar maple leaves and branches

 

PO: Sycamore (Platanus occidentalis): large, pointed lobes; white, gray & green bark

American Sycamore leaves

 

LT: Tulip Poplar (Liriodendron tulipifera): 3 squared-off lobes; straight ridged grayish bark

Yellow-poplar leaves and fruit

 

Pinnately lobed: plated light bark (white oaks) or dark thick furrowed bark (black/red)

QR: Northern Red Oak (Quercus rubra): Thin smooth leaf, pointed shallow lobes; Dark bark with smooth streaks; smooth tight buds and acorn cap

QV: Black Oak (Quercus velutina): leathery, two-tone, hairy, deeper lobes; rough bark & acorn caps; "hairy" buds; yellowish underbark

Leaves and acorns of northern red and black oaks

 

QA: White Oak (Quercus alba): rounded lobes, whitish plated bark

White oak leaves and acorns

 

QM: Chinkapin Oak (Quercus muhlenbergii): wavy margins (rounded shallow lobes); whitish plated bark

Chinkapin oak and acorn

 

Simple Leaves, Toothed

TA: Basswood (Tilia americana): [also above] heart-shaped, thin; furrowed light brown bark; often clumped

FG: Beech (Fagus grandifolia): thin pointed oblong, few coarse teeth; straight raised veins; smooth gray bark; icepick bud

American beech leaves, branches and seeds

 

PS: Black Cherry (Prunus serotinal): pointed oblong, finely toothed, wavy margins, dark & shiny; dark thin plated bark with light horizontal lenticels (raised lines)

Black cherry leaves and berries

 

OV: Hophornbeam (Ironwood) (Ostrya virginiana): lance-shaped, double-toothed; loose shaggy bark; green buds

Hophornbeam leaves

 

CR: American hornbeam (Carpinus caroliniana): Ironwood, Bluebeech, musclewood, lance-shaped, double-toothed; smooth gray sinewy bark; rusty brown buds

American hornbeam leaves

 

Elms: long-pointed oval larger at rounded, asymmetrical base, double-toothed, rough

UA: American Elm (Ulmus americana): thick corky bark with light layers; twigs & buds light brown, fuzzy

American elm leaves, flowers and samaras

 

UF: Slippery Elm (Ulmus fulva): dark green and coarsely hairy below; thick bark without light layers, inner bark slippery; twigs and buds very hairy; buds very dark

Slippery elm leaves and samaras

 

CT: Hackberry (Celtis occidentalis): pointed oval, rounded base, thin, single-toothed; gray bark has sharply raised bumps & ridges

Hackberry leaves and berries

 

Pinnately Compound Leaves (alternate except for ash)

FA: White Ash (Fraxinus americana): opposite leaves, 5-9 leaflets untoothed or rounded teeth; fissured gray bark; small dark flattened bud

White ash leaves, pistillate and staminate flowers

 

AN: Boxelder (Acer negundo): 3-5 notched leaflets; poison ivy-like; rough light brown bark

Boxelder leaves

 

JN: Black Walnut (Juglans nigra): 7-17 leaflets (most); thick furrowed rough brown bark

Black walnut leaves and nuts

 

Hickories: alternate leaves; 5-11 leaflets sharply toothed

CA: Bitternut (Carya cordiformis): 7-11 leaflets; smooth ridged bark; "candleflame" bud; thin yellowish pointed fruit husk

Bitternut hickory leaves and nuts

 

CG: Pignut (Carya glabra): 5-7 leaflets, smooth; ridged diamond pattern bark; bud small, oval; fruit narrow at base, husk smooth, dark

Pignut hickory leaves, branches and nuts

 

CO: Shagbark (Carya ovata): 5 leaflets, hairy below on primary vein; distal leaflets larger bark gray, hard loose plates; large oval hairy dark bud; thick ridged husk

Shagbark hickory leaves and branch

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