Forest Trees
of Illinois

THIRD EDITION

By Robert H. Mohlenbrock
Department of Botany, Southern Illinois University

Photography by John A. Richardson and Robert H. Mohlenbrock
Illustrations by Miriam Wysong Meyer and Fredda J. Burton
Southern Illinois University

Printed by authority of the State of Illinois
Issued by
DEPARTMENT OF CONSERVATION
Division of Forestry

14
(17943—10M—4-80)

TABLE OF CONTENTS

[Acknowledgments] 4 [Introduction] 5 [Illustrated Glossary] 6 [Key to the Trees of Illinois in Spring, Summer, and Fall] 9 [Key to the Trees of Illinois in Winter] 27 [Trees of Illinois] 38 [Special Places to Study Trees] 318 [White Oak, the State Tree of Illinois] 322 [Illinois Big Tree Champions] 323 [Index to Common and Scientific Names] 324 [District Foresters] 330

Acknowledgments

I am grateful to the late Mr. Fred Siemert, State Forester of the Illinois Division of Forestry, for suggesting the need for a new “Forest Trees of Illinois.” The first and second editions of this work have been immensely popular, and the need for a third edition is gratifying.

This third edition is only slightly modified from the second. A few illustrations and bark photographs have been substituted, and the key has been improved in places. New material has been added to the description of the water hickory.

I wish to give thanks to Mr. Al Mickelson of the Illinois Division of Forestry for encouraging this third edition, and to his assistants, Mr. John Sester and Mr. Ernest Kunze, for editing it for publication. Mark Mohlenbrock has redrawn the leaves and fruit illustrated on pages [101] and [169].

Introduction

The initial edition of Forest Trees of Illinois was written in 1927 by W. R. Mattoon and R. B. Miller, two prominent foresters in the state at that time. This was revised in 1955 by Dr. George Damon Fuller, then of the Illinois State Museum, and E. E. Nuuttila, State Forester of Illinois.

In 1973, I prepared the first edition of the new Forest Trees of Illinois with new text, keys, photographs, and illustrations. An updated second edition was published in 1978. Because of the heavy demand for this work, this third edition has been prepared.

Woody plants are usually divided into trees and shrubs, but the difference between these growth forms is not always distinct. In this work, we consider a plant to be of tree stature if it has a single erect trunk which branches above the ground to form a crown. It must have a diameter of at least 3 inches 4½ feet above the ground and an overall height of 12 feet. Some of the plants included in this work are borderline between trees and shrubs. The height of a plant may be influenced by its geography. Thus, the Gray Dogwood (Cornus racemosa) in extreme southern Illinois may reach the dimensions of a small tree, but this same species in northern Illinois is also of a shrubby stature.

Almost every kind of plant in the world is known by a Common Name and a Latin Name. The Common Name is the one used locally by residents of the area. It is of limited value because people in different areas sometimes have different names for the same plant. For example, one of the trees in Illinois is known by some as the Ironwood, by others as the Blue Beech, by others as the American Hornbeam, and by still others as the Musclewood Tree. Then again, the name Ironwood applies to at least two different kinds of trees in Illinois. The Latin Name for each kind of tree is known the World over by the same name. Actually, the Latin Name is composed of two words, the genus name, which is always capitalized, and the specific epithet, which is not capitalized.

Of all the kinds of plants in the World, none is so well-loved, so stately and majestic, as a forest tree. More and more people each year are vacationing and seeking outdoor recreation. Many of them “take to the woods” for their leisure, because the forests of our state hold an unending fascination to many who enter them.

Moreover, trees provide us with building material for our homes, shade for our lawns and parks, and hundreds of other products used in our everyday living.

To know the trees we encounter is to enhance our appreciation for them. The purpose of FOREST TREES OF ILLINOIS is to bring to Illinoisans a means of identifying the trees that grow in this state.

Illustrated Glossary

In order to distinguish one kind of tree from another, it is necessary to learn the major characteristics which the forest trees of Illinois may possess. Illustrated below are several of the most commonly encountered characteristics of leaves and twigs. A thorough understanding of these structures will insure a quicker and more accurate identification.

On the pages following the illustrated glossary are keys to the trees of Illinois. A key is a botanical device which enables the user, through proper selection of a series of choices, to identify a specimen at hand. Separate keys are provided for trees during the spring, summer, and autumn seasons and during the winter season. Begin at the first pair of number 1’s, choose the statement that best fits the unknown specimen, and then go to the next pair of statements beneath. Continue this same procedure until the name of the plant is reached.

LEAF FORMS AND ARRANGEMENT SIMPLE PINNATELY COMPOUND PALMATELY COMPOUND DOUBLY PINNATELY COMPOUND OPPOSITE ALTERNATE WHORLED LEAF SHAPES LANCEOLATE OBLANCEOLATE OBLONG ELLIPTICAL OVATE OBOVATE

WINTER TWIG CHARACTERS

WINTER TWIG CHARACTERS BUD SCALE TERMINAL BUD LATERAL BUD LEAF SCAR LENTICELS BUNDLE TRACES {LEAF LAYERS} UPPER EPIDERMIS PALISADE LAYER RIBS AND VEINS SPONGY LAYER STOMA LOWER EPIDERMIS LEAF TIPS ACUTE OBTUSE LONG-TAPERING LEAF EDGES PINNATELY LOBED WAVY TOOTHED DOUBLY TOOTHED SMOOTH LEAF BASES HEART-SHAPED TRUNCATE ASYMMETRICAL ROUNDED TAPERING

Key to the Trees of Illinois in Spring, Summer, and Fall

1. Leaves needle-like or scale-like [Group A] 1. Leaves broad and flat, never needle-like or scale-like. 2. Leaves compound (divided into 3 or more leaflets) [Group B] 2. Leaves simple. 3. Leaves opposite or whorled [Group C] 3. Leaves alternate. 4. Leaves neither toothed nor lobed [Group D] 4. Leaves toothed or lobed or both. 5. Leaves toothed but not lobed [Group E] 5. Leaves lobed [Group F]

GROUP A

Leaves needle-like or scale-like, often evergreen.

1. Leaves in clusters of 2 or more. 2. Leaves in clusters of 10 or more, falling off during autumn. 3. Leaves blue-green; cone-scales smooth [Larix laricina] 3. Leaves bright green; cone-scales hairy [Larix decidua] 2. Leaves in clusters of 2-5, evergreen. 4. Leaves in clusters of 5 [Pinus strobus] 4. Leaves in clusters of 2-3. 5. Leaves in clusters of 2. 6. Most or all the leaves less than 3 inches long, usually twisted. 7. Leaves up to 1½ inches long; sheath at base of leaves not longer than ⅛ inch [Pinus banksiana] 7. Leaves 2-3 inches long; sheath at base of leaves at least ⅓ inch long [Pinus sylvestris] 6. Most or all the leaves longer than 3 inches, rarely twisted. 8. Leaves mostly less than 5 inches long; cone-scale with a small spine [Pinus echinata] 8. Leaves mostly more than 5 inches long; cone-scale without a spine [Pinus resinosa] 5. Leaves in clusters of 3. 9. Leaves flexible, mostly less than 5 inches long; sheath at base of leaves about ¼ inch long [Pinus echinata] 9. Leaves stiff, mostly more than 5 inches long; sheath at base of leaves about 1 inch long [Pinus taeda] 1. Leaves solitary. 10. Leaves evergreen, of 2 types, some of them scale-like and about ⅛ inch long, some of them needle-like and up to ⅓ inch long [Juniperus virginiana] 10. Leaves falling off in autumn, all needle-like, usually at least ½ inch long. 11. Leaves 3-angled. 12. Leaves blue-green [Larix laricina] 12. Leaves bright green [Larix decidua] 11. Leaves flat [Taxodium distichum]

GROUP B

Leaves broad and flat, never needle-like or scale-like, compound.

1. Leaves alternate. 2. Leaflets 3 [Ptelea trifoliata] 2. Leaflets 5 or more. 3. Main stalk between leaflets winged on either side [Rhus copallina] 3. Main stalk between leaflets not winged. 4. Leaves with an even number of leaflets, often doubly compound. 5. Leaflets not more than ½ inch wide. 6. Pods usually 12 inches long or longer, with 6 or more seeds [Gleditsia triacanthos] 6. Pods 1-2 inches long, with 1-3 seeds [Gleditsia aquatica] 5. Some or all the leaflets at least one inch broad. 7. Leaves doubly compound; leaflets smooth along the edges; leaves without a foul odor when crushed [Gymnocladus dioicus] 7. Leaves once compound; leaflets usually with a few coarse teeth along the edges; leaves with a foul odor when crushed [Ailanthus altissima] 4. Leaves with an odd number of leaflets, once compound (twice compound in [Aralia spinosa], which has prickly leafstalks). 8. Leaflets without teeth along the edges. 9. Leaflets less than 1 inch broad and 2 inches long; twigs with short spines at base of leaf stalks [Robinia pseudoacacia] 9. Leaflets up to 4 inches long and up to 2 inches broad; twigs without spines. 10. Some or all the leaflets alternate; base of leafstalk conspicuously swollen [Cladrastis lutea] 10. All the leaflets opposite; base of leafstalk not swollen [Rhus vernix] 8. Leaflets toothed along the edges. 11. Leaves doubly compound, often with small prickles on the leafstalks and on some of the veins [Aralia spinosa] 11. Leaves once compound, without prickles. 12. All leaves with 11 or more leaflets. 13. Leafstalks and lower surface of leaves completely smooth [Rhus glabra] 13. Leafstalks and lower surface of leaves (at least on the veins) hairy. 14. Pith of twigs chambered when cut lengthwise. 15. Pith pale brown; bark dark brown, with roughened ridges [Juglans nigra] 15. Pith dark brown; bark gray, with smooth ridges [Juglans cinerea] 14. Pith of twigs solid. 16. Leaves strongly aromatic when crushed; twigs not covered with velvety hairs. 17. Bud scales with yellow hairs; nut 1½ to 2 times longer than broad [Carya illinoensis] 17. Bud scales without yellow hairs; nut about as broad as long [Carya aquatica] 16. Leaves not aromatic when crushed; twigs covered with velvety hairs [Rhus typhina] 12. Some or all leaves with less than 11 leaflets. 18. Buds with 4-6 scales arranged in pairs; most of the leaves with at least 9 leaflets. 19. Terminal leaflet without a stalk or with a very short stalk; buds mustard-yellow [Carya cordiformis] 19. Terminal leaflet with a well-developed stalk; bud reddish-brown [Carya aquatica] 18. Buds with 6 or more overlapping scales; most of the leaves with fewer than 9 leaflets (except sometimes in [Carya tomentosa] and [Carya laciniosa]), never with 11 leaflets. 20. Teeth along the leaf margin with small tufts of hairs [Carya ovata] 20. Teeth along the leaf margin without small tufts of hairs. 21. Lower surface of leaflets densely and uniformly hairy. 22. Stalk to which leaflets are attached densely hairy; bark tight, not shaggy [Carya tomentosa] 22. Stalk to which leaflets are attached smooth or sparsely hairy; bark shaggy at maturity [Carya laciniosa] 21. Lower leaf surface smooth, or with tufts of hairs in the vein axils, or sometimes sparsely hairy along the veins. 23. Scales of buds, stalk of leaves, and young twigs rusty-hairy or -scaly [Carya texana] 23. Rusty hairs and scales not present. 24. Leaflets mostly 5; bud scales without hairs at the tip; bark tight, not peeling [Carya glabra] 24. Leaflets mostly 7; bud scales with hairs at the tip; bark peeling at maturity [Carya ovalis] 1. Leaves opposite. 25. Leaves palmately compound. 26. Leaflets mostly 7; buds very sticky [Aesculus hippocastanum] 26. Leaflets mostly 5; buds not sticky. 27. Fruit prickly; flowers yellow [Aesculus glabra] 27. Fruit smooth; flowers red [Aesculus discolor] 25. Leaves pinnately compound, or sometimes with only 3 leaflets. 28. Leaflets usually 3, or sometimes 5; twigs green or glaucous [Acer negundo] 28. Leaflets usually 7 or more, sometimes 5; twigs not green. 29. Some or all of the twigs square [Fraxinus quadrangulata] 29. Stems not square. 30. Leaflets without stalks [Fraxinus nigra] 30. Leaflets stalked. 31. Stalks of the leaflets winged. [Fraxinus pennsylvanica var. subintegerrima] 31. Twigs and leafstalks smooth 32. Leaflets whitened on the lower surface [Fraxinus americana] 32. Leaflets green or yellow-brown on the lower surface [Fraxinus tomentosa]

GROUP C

Leaves broad and flat, never needle-like or scale-like, simple, opposite or whorled.

1. Leaves (or some of them) in whorls of 3. 2. Leaves with a bad odor when crushed; flowers with conspicuous purple spots [Catalpa bignonioides] 2. Leaves without a bad odor when crushed; flowers merely lined with purple [Catalpa speciosa] 1. Leaves opposite. 3. Leaves at least 6 inches long and 6 inches broad, heart-shaped at the base, never palmately lobed [Paulownia tomentosa] 3. Leaves usually less than 6 inches long and 6 inches broad, not heart-shaped at the base or, if slightly heart-shaped, then also palmately lobed. 4. Leaves palmately lobed. 5. Leafstalk with milky sap when broken [Acer platanoides] 5. Leafstalk without milky sap. 6. Areas between leaf lobes mostly V-shaped; leaves usually silvery or white on the lower surface. 7. Leaves deeply divided, the areas between the lobes extending more than half-way to the midvein [Acer saccharinum] 7. Leaves shallowly divided, the areas between the lobes extending less than half-way to the midvein. 8. Leaves completely covered with a white felt on the lower surface [Acer rubrum var. drummondii] 8. Leaves smooth or sparsely hairy on the lower leaf surface [Acer rubrum] 6. Areas between leaf lobes mostly U-shaped; leaves green or paler on the lower surface, not white or silvery. 9. Leaves with the edges drooping. 10. Leaves green on the lower surface; small leafy outgrowths sometimes present at the base of the leafstalk [Acer nigrum] 10. Leaves grayish on the lower surface; small leafy outgrowths at the base of the leafstalk absent [Acer barbatum] 9. Leaves flat, the edges not drooping [Acer saccharum]

4. Leaves not lobed. 11. Leaves toothed along the edges. 12. Edges of leaves regularly toothed from tip of leaf to base; leaves usually short-pointed or rounded at the tip. 13. Buds, leafstalks, and veins on the lower surface of the leaf covered with rusty hairs [Viburnum rufidulum] 13. Buds, leafstalks, and veins on the lower surface of the leaf without rusty hairs. 14. Leaf stalks wavy along the edges [Viburnum lentago] 14. Leaf stalks not wavy along the edges. 15. Branches spine-tipped [Rhamnus cathartica] 15. Branches not spine-tipped [Viburnum prunifolium] 12. Edges of leaves toothed only above the middle of the leaf; leaves tapering to a long point [Forestiera acuminata] 11. Leaves not toothed along the edges. 16. Upper surface of leaves rough to the touch [Cornus drummondii] 16. Upper surface of leaves smooth. 17. Leaves with deeply impressed veins on the upper surface; lower surface of leaves gray or whitish. 18. Leaves often nearly as broad as long; flowers surrounded by 4 large, white bracts; berries red; twigs green [Cornus florida] 18. Leaves longer than broad; flowers not surrounded by 4 large, white bracts; berries white; twigs gray [Cornus racemosa] 17. Leaves without deeply impressed veins; leaves often paler on the lower surface, but not gray or whitish [Forestiera acuminata]

GROUP D

Leaves broad and flat, never needle-like or scale-like, simple, alternate, neither toothed nor lobed.

1. Most or all of the leaves more than six inches long. 2. Leaves long-tapering to the base; winter buds elongated, about ⅛ inch long, covered with reddish-brown hairs [Asimina triloba] 2. Leaves rounded or only short-tapering to the base; winter buds either ½ inch long and white-hairy, or rounded and yellow. 3. Leafstalks usually more than 1½ inches long, hairy; buds nearly round, yellow [Nyssa aquatica] 3. Leafstalks usually less than 1½ inches long, smooth; buds elongated, white-hairy [Magnolia acuminata] 1. Most or all of the leaves less than six inches long. 4. Leafstalks with milky sap; twigs usually bearing small spines near the point of the leaf attachment [Maclura pomifera] 4. Leafstalks without milky sap; twigs not spiny. 5. Leaves spicy-aromatic when crushed, twigs green [Sassafras albidum] 5. Leaves not spicy-aromatic when crushed; twigs usually not green. 6. Leaves distinctly asymmetrical at base, usually obviously 3-nerved from the base. 7. Leaves usually at least twice longer than broad, rounded at the base [Celtis laevigata] 7. Leaves usually less than twice longer than broad, more or less heart-shaped at the base [Celtis tenuifolia] 6. Leaves symmetrical at the base, with a single main vein. 8. Leaves heart-shaped at the base, about as broad as long [Cercis canadensis] 8. Leaves rounded or tapering to the base, longer than broad. 9. Many of the leaves clustered near the tips of the twigs. 10. Leaves abruptly short-pointed at the tip [Nyssa sylvatica] 10. Leaves tapering to the tip. 11. Veins of leaf deeply impressed, strongly arching toward the tip of the leaf; fruit a berry [Cornus alternifolia] 11. Veins of leaf not deeply impressed nor strongly arching toward the tip of the leaf; fruit an acorn. 12. Lower surface of leaves hairy; leafstalk usually hairy; leaves usually one inch wide or wider [Quercus imbricaria] 12. Lower surface of leaves smooth except for the veins; leafstalk usually smooth; leaves usually less than one inch wide [Quercus phellos] 9. Leaves not clustered near the tips of the twigs. 13. Leaves usually with 10 or more pairs of veins; leafstalks often 1½ inches long or longer [Nyssa aquatica] 13. Leaves usually with 6-8 pairs of veins; leafstalks rarely as long as 1½ inches. 14. Leaves abruptly contracted to a short point at the tip. 15. Leaves usually about twice as long as broad; fruit an orange berry about 1 inch in diameter [Diospyros virginiana] 15. Leaves usually less than twice as long as broad; fruit a blue berry up to ½ inch in diameter [Nyssa sylvatica] 14. Leaves gradually tapering to the tip [Rhamnus caroliniana]

GROUP E

Leaves broad and flat, never needle-like or scale-like; leaves simple, alternate, toothed but not lobed.

1. Leaves asymmetrical at the base. 2. Leaves with 3 main veins arising from the base of the blade. 3. Edge of leaf with low, rounded teeth or merely wavy [Hamamelis virginiana] 3. Edge of leaf sharply or finely toothed. 4. Most of all the leafstalks less than one inch long; trunk usually warty. 5. Upper surface of leaf very rough to the touch; leaves thick and leathery. 6. Leaves tapering to a long point at the tip; most or all of the blades 3 inches long or longer [Celtis occidentalis] 6. Leaves tapering to a short point at the tip; most or all of the blades less than 3 inches long [Celtis tenuifolia] 5. Upper surface of leaf smooth or only slightly rough to the touch; leaves thin and membranaceous. 7. Leaves at least three times longer than broad [Celtis laevigata] 7. Leaves less than three times longer than broad. 8. Some or all the leaves 3 inches long or longer [Celtis occidentalis] 8. Leaves less than 3 inches long [Celtis tenuifolia] 4. Leafstalks more than 1 inch long. 9. Leaves smooth on the lower surface except for small tufts of hairs where the veins meet [Tilia americana] 9. Leaves hairy on the lower surface. 10. Lower surface of leaves white [Tilia heterophylla] 10. Lower surface of leaves green [Tilia americana]

2. Leaves with one main vein arising from the base of the blade. 11. Some of the twigs with corky wings. 12. Some or all the leaves four inches long or longer; leaf-stalks more than ⅛ inch long [Ulmus thomasii] 12. None of the leaves four inches long; leafstalks up to ⅛ inch long [Ulmus alata] 11. Twigs without corky wings. 13. Leaves very rough-hairy to the touch [Ulmus rubra] 13. Leaves smooth or soft to the touch. 14. Edge of leaf doubly toothed (each tooth divided into a second small tooth). 15. Leaves distinctly one-sided at the base; leafstalks often smooth [Ulmus americana] 15. Leaves only slightly one-sided at the base; leafstalks hairy. 16. Bark of trunk with sinewy ridges; fruit enclosed in flat, 3-lobed bracts; lower lateral veins of leaf unbranched [Carpinus caroliniana] 16. Bark of trunk broken into scales; fruit surrounded by inflated, bladdery bracts; lower lateral veins of leaf branched [Ostrya virginiana] 14. Edge of leaf singly toothed. 17. Leaves smooth on the lower surface; leafstalks smooth [Ulmus pumila] 17. Leaves hairy on the lower surface, at least where the veins meet; leafstalks usually hairy [Planera aquatica] 1. Leaves symmetrical at the base. 18. Leaves with 2-4 irregular teeth along the edges. 19. Leaves usually with 10 or more pairs of veins; leaf stalks often 1½ inches long or longer [Nyssa aquatica] 19. Leaves usually with 6-8 pairs of veins; leaf stalks rarely as long as 1½ inches [Nyssa sylvatica] 18. Leaves more regularly toothed with more than 4 teeth along the edges. 20. Leafstalks with milky sap when broken. 21. Leaf stalks and lower surface of leaf with long hairs [Broussonetia papyrifera] 21. Leaf stalks and lower surface of leaf smooth or with short hairs. 22. Lower leaf surface hairy between the veins [Morus rubra] 22. Lower leaf surface smooth or hairy only on the veins [Morus alba] 20. Leafstalks without milky sap when broken. 23. Leaves at least 4 times as long as broad. 24. Leafstalks less than ⅛ inch long; leaves irregularly toothed along the edges [Salix interior] 24. Leafstalks more than ⅛ inch long; leaves regularly toothed along the edges. 25. Leaves green on the lower surface [Salix nigra] 25. Leaves whitish on the lower surface. 26. Each leaf with a pair of leaf-like stipules at the base of the leafstalk [Salix caroliniana] 26. Each leaf without a pair of leaf-like stipules [Salix amygdaloides] 23. Leaves less than 4 times as long as broad. 27. Leaves as broad as long or broader. 28. Leaf stalks not flattened. 29. Leaves strongly whitened on the lower surface, not heart-shaped at the base [Populus alba] 29. Leaves not strongly whitened on the lower leaf surface, heart-shaped at the base [Populus heterophylla] 28. Leaf stalks flattened. 30. Leaves basically triangular in shape, coarsely toothed [Populus deltoides] 30. Leaves basically ovate or spherical, coarsely or finely toothed. 31. Leaves with 20 or more fine teeth along the edges [Populus tremuloides] 31. Leaves with up to 15 coarse teeth along the edges. [Populus grandidentata] 27. Leaves longer than broad. 32. Twigs usually with sharp spines. 33. Leaves broadest below the middle; fruit a small apple. 34. Many of the leaves narrowly oblong to narrowly elliptic [Malus angustifolia] 34. Most of the leaves ovate to oval to broadly lance-shaped. 35. Twigs and young leaves densely hairy [Malus ioensis] 35. Twigs and young leaves smooth or nearly so [Malus coronaria] 33. Leaves broadest at or above the middle; fruit a hawthorn. 36. Leaves broadest at the middle; leafstalks one inch long or longer [Crataegus viridis] 36. Leaves broadest above the middle; leafstalks up to ¾ inch long. 37. Leaves leathery, smooth on both surfaces [Crataegus crus-galli] 37. Leaves not leathery, usually somewhat hairy on the lower surface [Crataegus punctata] 32. Twigs not spiny. 38. Some of the twigs with corky wings. 39. Some or all the leaves 4 inches long or longer; leafstalks more than ⅛ inch long [Ulmus thomasii] 39. None of the leaves 4 inches long; leafstalks up to ⅛ inch long [Ulmus alata] 38. None of the twigs with corky wings. 40. Individual teeth along edge of the leaf at least ¼ inch long. 41. Most of the veins not reaching to the tip of each leaf; lower surface of leaf usually silvery-white [Quercus bicolor] 41. Most of the veins projecting to the tip of each leaf; lower surface of leaf green or pale, but usually not silvery-white. 42. Leaves usually with sharp-pointed teeth. 43. Fruit an acorn; lower leaf surface usually covered with very short hairs [Quercus muhlenbergii] 43. Fruit enclosed in a prickly bur; lower leaf surface smooth or nearly so [Castanea dentata] 42. Leaves usually with somewhat rounded teeth. 44. Cup of acorn at least 1 inch across; trunk whitish to gray [Quercus michauxii] 44. Cup of acorn less than 1 inch across; trunk brown to black [Quercus prinus] 40. Individual teeth along edge of leaf up to ⅛ inch long. 45. Some of the leaves produced from short, stubby shoots along the main twigs [Ilex decidua] 45. Twigs without short, stubby side shoots. 46. Leafstalks with 1 or more small glands (“bumps”), usually near the point of attachment to the blade. 47. Each tooth along the edge of the leaf bearing a small, reddish-brown gland. 48. Some or all leaves one inch broad or broader. 49. Leaves flat [Prunus hortulana] 49. Leaves more or less folded down the middle [Prunus munsoniana] 48. None of the leaves as much as one inch broad [Prunus angustifolia] 47. Teeth along the edge of the leaf not bearing a gland. 50. Leaves usually with a dull, wrinkled surface; fruit a plum [Prunus americana] 50. Leaves usually appearing smooth and rather shiny; fruit an elongated cluster of small cherries. 51. Teeth along edge of leaf curving inward, usually rather blunt [Prunus serotina] 51. Teeth along edge of leaf pointing outward, usually sharp-pointed [Prunus virginiana] 46. Leafstalks not bearing glands. 52. Leaves doubly toothed along the edges. 53. Bark peeling off into papery strips or layers; leaves usually about two-thirds as broad as long or broader. 54. Bark yellowish, silvery-gray, or creamy-white. 55. Bark yellowish or silvery-gray; leaves with 8 or more pairs of veins [Betula lutea] 55. Bark creamy-white; leaves with no more than 7 pairs of veins [Betula papyrifera] 54. Bark reddish-brown [Betula nigra] 53. Bark broken into small plates, or smooth and sinewy, not peeling off into papery strips or layers. 56. Bark of trunk with sinewy ridges; fruit enclosed in flat, 3-lobed bracts; lower lateral veins of leaf unbranched [Carpinus caroliniana] 56. Bark of trunk broken into scales; fruit enclosed in inflated, bladdery bracts; lower lateral veins of leaf branched [Ostrya virginiana] 52. Leaves singly toothed along the edges. 57. Leaves heart-shaped at the base. 58. Leaves up to six inches long and nearly as broad [Populus heterophylla] 58. Leaves not more than four inches long and about half as broad. 59. Leaves bronze as they unfold; leafstalk smooth [Amelanchier laevis] 59. Leaves densely white-hairy as they unfold; leafstalk somewhat hairy [Amelanchier arborea] 57. Leaves rounded or tapering to the base, not heart-shaped. 60. Teeth along edge of leaf widely spaced, at least ¼ inch apart [Fagus grandifolia] 60. Teeth along edge of leaf closely and regularly spaced. 61. Leafstalk hairy; fruit fleshy. 62. Leaves shiny on the upper surface; leafstalks ½ inch long or longer [Rhamnus caroliniana] 62. Leaves dull on the upper surface; leafstalks up to ¼ inch long [Planera aquatica] 61. Leafstalk smooth at maturity; fruit dry and variously winged. 63. Some of the leaves three inches long or longer; fruit 4-winged or a woody “cone.” 64. Leaves pointed at the tip; fruit 4-winged [Halesia carolina] 64. Leaves rounded at the tip; fruit a woody “cone” [Alnus glutinosa] 63. Leaves less than 3 inches long; fruit surrounded by a flat wing [Ulmus pumila]

GROUP F

Leaves broad and flat, never needle-like or scale-like; leaves simple, alternate, lobed.

1. Leafstalks with milky sap when broken. 2. Leafstalks and lower surface of leaf with long hairs [Broussonetia papyrifera] 2. Leafstalks and lower surface of leaf smooth or with short hairs. 3. Lower leaf surface hairy between the veins [Morus rubra] 3. Lower leaf surface smooth or hairy only on the veins [Morus alba] 1. Leafstalks without milky sap when broken. 4. Twigs usually with sharp spines. 5. Leaves broadest at the middle or above the middle. 6. Leaves broadest at the middle; lower surface of leaf smooth except for a few tufts of hairs near the veins [Crataegus viridis] 6. Leaves broadest above the middle; lower surface of leaf hairy throughout [Crataegus punctata] 5. Leaves broadest below the middle. 7. Leaves hairy throughout on the lower surface. 8. Leaves mostly tapering to the base; fruit a crab apple [Malus ioensis] 8. Leaves rounded at the base; fruit a hawthorn. 9. Fruit with pitted seeds; flowers appearing in late May and June [Crataegus calpodendron] 9. Fruit without pitted seeds; flowers appearing in April or early May [Crataegus mollis] 7. Leaves smooth on the lower surface or hairy only on the veins. 10. Leaves tapering to the base. 11. Leaves oval to ovate to broadly lance-shaped [Malus coronaria] 11. Leaves narrowly oblong to narrowly elliptic [Malus angustifolia] 10. Leaves rounded at the base. 12. Leaves blue-green; fruit spherical or nearly so [Crataegus pruinosa] 12. Leaves green; fruit shaped like a little apple [Malus coronaria] 4. Twigs without spines. 13. Leaves star-shaped [Liquidambar styraciflua] 13. Leaves not star-shaped. 14. Leaves 4-lobed, smooth on both surfaces [Liriodendron tulipifera] 14. Leaves more than 4-lobed, hairy on one or both surfaces. 15. Leaves palmately lobed and veined. 16. Leaves densely coated with white felt on the lower surface [Populus alba] 16. Leaves without a coat of white felt on the lower surface [Platanus occidentalis] 15. Leaves pinnately lobed and veined. 17. Lobes of leaf with bristle-tips. 18. Leaves broadest above the middle [Quercus marilandica] 18. Leaves broadest at or below the middle. 19. Leaves hairy throughout on the lower surface. 20. Lower surface of leaves with gray hairs; base of leaf blade usually broadly rounded. 21. Leaves with 5-11 more or less equal lobes, the uppermost lobe not strongly curved [Quercus pagodaefolia] 21. Leaves with 3-5 more or less unequal lobes, the uppermost lobes often strongly curved [Quercus falcata] 20. Lower surface of leaves with rusty hairs; base of leaf blade not broadly rounded [Quercus velutina] 19. Leaves smooth on the lower surface or hairy only next to the veins. 22. Leaves divided less than halfway to the middle. 23. Leafstalks hairy; buds hairy, gray [Quercus velutina] 23. Leafstalks smooth; buds smooth, reddish-brown [Quercus rubra] 22. Leaves divided more than halfway to the middle. 24. Leafstalks hairy; cup of acorn fringed around the edge [Quercus velutina] 24. Leafstalks smooth; cup of acorn not fringed around the edge. 25. Lower surface of leaves with large tufts of hairs in the vein axils. 26. Cup of acorn saucer-shaped. 27. Cup of acorn up to ½ inch broad. [Quercus palustris] 27. Cup of acorn more than ½ inch broad [Quercus shumardii] 26. Cup of acorn top-shaped. 28. Cup of acorn enclosing about ⅓ the nut at most [Quercus shumardii] 28. Cup of acorn enclosing more than one-third of the nut [Quercus ellipsoidalis] 25. Lower surface of leaves smooth or with small tufts in hairs in the vein axils [Quercus coccinea] 17. Lobes of leaf with round tips, not bristle-tipped. 29. Leaves smooth on the lower surface [Quercus alba] 29. Leaves hairy on the lower surface. 30. Upper three lobes of leaf squarish, forming a cross; twigs hairy [Quercus stellata] 30. Leaves without three squarish lobes at the upper end; twigs smooth or nearly so. 31. Edge of acorn cup with a fringe [Quercus macrocarpa] 31. Edge of acorn cup not fringed [Quercus lyrata]

Key to Illinois Trees in Winter

1. Green leaves present during winter, needle-like or scale-like [Group G] 1. Green leaves absent during winter [Group H]

GROUP G

1. Leaves in clusters of 2 or more. 2. Leaves in clusters of 5 [Pinus strobus] 2. Leaves in clusters of 2-3. 3. Leaves in clusters of 2. 4. Most or all the leaves less than 3 inches long, usually twisted. 5. Leaves up to 1½ inches long; sheath at base of leaves not longer than ⅛ inch [Pinus banksiana] 5. Leaves 2-3 inches long; sheath at base of leaves at least ⅓ inch long [Pinus sylvestris] 4. Most or all the leaves longer than 3 inches, rarely twisted. 6. Leaves mostly less than 5 inches long; cone-scale with a small spine [Pinus echinata] 6. Leaves mostly more than 5 inches long; cone-scale without a spine [Pinus resinosa] 3. Leaves in clusters of 3. 7. Leaves flexible, mostly less than 5 inches long; sheath at base of leaves about ¼ inch long [Pinus echinata] 7. Leaves stiff, mostly more than 5 inches long; sheath at base of leaves about 1 inch long [Pinus taeda] 1. Leaves solitary, of 2 types, some of them scale-like and about ⅛ inch long, some of them needle-like and up to ⅓ inch long [Juniperus virginiana]

GROUP H

1. Leaf scars absent (scars which resemble leaf scars present but lacking bundle scars) [Taxodium distichum] 1. Leaf scars present. 2. Leaf scars in whorls of 3 [Catalpa spp.] 2. Leaf scars opposite or alternate. 3. Leaf scars opposite. 4. Bundle scar 1 [Forestiera acuminata] 4. Bundle scars 3 or more. 5. Bundle scars usually 9 or more. 6. Pith hollow or sometimes chambered [Paulownia tomentosa] 6. Pith solid, not chambered. 7. Twigs 4-sided [Fraxinus quadrangulata] 7. Twigs not 4-sided. 8. Twigs hairy. 9. Leaf scars notched at top. 10. Twigs with conspicuous large lenticels; trunks swollen at the base [Fraxinus tomentosa] 10. Twigs with inconspicuous lenticels; trunks not swollen at the base [Fraxinus americana] 9. Leaf scars more or less straight across at the top [Fraxinus pennsylvanica] 8. Twigs smooth. 11. Leaf scars oval; buds brownish-black to black [Fraxinus nigra] 11. Leaf scars half-round; buds brown. 12. Leaf scars notched at the top [Fraxinus americana] 12. Leaf scars more or less straight across the top [Fraxinus pennsylvanica var. subintegerrima] 5. Bundle scars usually 3-7 (sometimes 9 in [Acer negundo]). 13. Leaf scars very broad, usually at least ⅓ inch across. 14. Bark smooth [Aesculus discolor] 14. Bark becoming furrowed and scaly [Aesculus glabra] 13. Leaf scars narrow, less than ⅓ inch across. 15. Buds with 2 exposed outer scales. 16. Twigs gray or gray-brown. 17. Buds long and narrow, at least 5 times longer than broad [Viburnum lentago] 17. Buds shorter, at most 3 times longer than broad. 18. Buds reddish-brown. 19. Buds smooth or scurfy [Viburnum prunifolium] 19. Buds hairy [Viburnum rufidulum] 18. Buds light brown. 20. Buds hairy [Cornus drummondii] 20. Buds smooth or nearly so [Cornus racemosa] 16. Twigs purple or orange-brown. 21. Twigs purplish [Cornus florida] 21. Twigs orange-brown, at least usually not purplish [Cornus racemosa] 15. Buds with more than 2 exposed scales. 22. Twigs green or glaucous [Acer negundo] 22. Twigs brown. 23. Buds rounded, several in a cluster; twigs red or orange. 24. Twigs hairy [Acer rubrum var. drummondii] 24. Twigs smooth. 25. Twigs with an unpleasant odor; bark scaly [Acer saccharinum] 25. Twigs without an unpleasant odor; bark not scaly [Acer rubrum] 23. Buds elongated; twigs brown or gray. 26. Ends of some twigs tapering to a spine [Rhamnus cathartica] 26. Ends of twigs not spiny. 27. Twigs (at least by the time they are 2 years old) pale gray-brown, dull [Acer nigrum] 27. Twigs pale reddish-brown, shiny. 28. Buds pointed at the tip [Acer saccharum] 28. Buds more or less rounded at the tip [Acer barbatum] 3. Leaf scars alternate. 29. Thorns or spines present. 30. Spines in pairs [Robinia pseudoacacia] 30. Spines solitary, although sometimes branched. 31. Spines scattered all along the twigs and branches [Aralia spinosa] 31. Spines not scattered all along the twigs and branches. 32. Thorns branched [Gleditsia spp.] 32. Thorns unbranched. 33. Buds pointed at the tip. 34. Twigs usually hairy [Malus ioensis] 34. Twigs usually smooth. 35. Buds with reddish scales [Malus coronaria] 35. Buds with chestnut-brown scales [Malus angustifolia] 33. Buds more or less rounded at the tip. 36. Terminal bud absent [Maclura pomifera] 36. Terminal bud present [Crataegus spp.] 29. Thorns or spines absent. 37. Pith chambered, at least at the nodes. 38. Leaf scars 3-lobed and usually with 3 groups of bundle scars. 39. Pith pale brown; leaf scars without velvety hairs at the top [Juglans nigra] 39. Pith chocolate-brown; leaf scars with velvety hairs at the top [Juglans cinerea] 38. Leaf scars half-round, not 3-lobed. 40. Pith chambered only at the nodes; stipular scars present. 41. Buds about ¼ inch long [Celtis occidentalis] 41. Buds about ⅛ inch long. 42. Twigs usually smooth; trees [Celtis laevigata] 42. Twigs usually hairy; shrubs [Celtis tenuifolia] 40. Pith chambered between the nodes as well as at most of the nodes; stipular scars absent. 43. Exposed bud scales 2 [Diospyros virginiana] 43. Exposed bud scales 4 [Halesia carolina] 37. Pith solid, although sometimes with diaphragms. 44. Pith with diaphragms. 45. Buds without bud scales [Asimina triloba] 45. Buds with 1 or more scales. 46. Bud scales 1-2; bundle scars 7 or more; stipular scars present. 47. Bud scale 1, hairy [Magnolia acuminata] 47. Bud scales 2, smooth [Liriodendron tulipifera] 46. Bud scales 3-several; bundle scars 3; stipular scars absent. 48. Buds about ¼ inch long [Nyssa sylvatica] 48. Buds up to 1 inch long [Nyssa aquatica] 44. Pith without diaphragms. 49. Bundle scar 1. 50. Twigs orange; bark reddish-brown [Larix decidua] 50. Twigs orange; bark reddish-brown [Larix laricina] 49. Bundle scars 2 or more. 51. Stipular scars forming a ring around the twig [Platanus occidentalis] 51. Stipular scars not forming a ring around the twig, or absent. 52. Twigs aromatic when cut. 53. Twigs green; buds generally smooth [Sassafras albidum] 53. Twigs orange-brown; buds generally hairy [Betula lutea] 52. Twigs not aromatic when cut. 54. Buds without scales. 55. Terminal buds larger than the rest of the buds. 56. Buds rusty-hairy or gray-woolly. 57. Buds rusty-hairy, 2-3 times longer than broad [Asimina triloba] 57. Buds gray-woolly, not much longer than broad [Malus ioensis] 56. Buds smooth or, if hairy, not conspicuously rusty-hairy or gray-woolly. 58. Leaf scars lobed; twigs without stipular scars. 59. Buds bright yellow [Carya cordiformis] 59. Buds brown or reddish-brown. 60. Terminal bud up to ½ inch long; twigs with orange lenticels [Carya illinoensis] 60. Terminal bud up to ¼ inch long; twigs with pale lenticels [Carya aquatica] 58. Leaf scars unlobed; twigs with stipular scars. 61. Buds pale brown; twigs often zig-zag [Hamamelis virginiana] 61. Buds light brown; twigs mostly straight [Rhamnus caroliniana] 55. Terminal buds smaller than other buds, or absent. 62. Pith reddish-brown; leaf scars often ½ inch across [Gymnocladus dioicus] 62. Pith not reddish-brown; leaf scars less than ½ inch across. 63. Milky sap present. 64. Twigs hairy. 65. Twigs velvety; pith yellow [Rhus typhina] 65. Twigs not velvety; pith whitish [Rhus copallina] 64. Twigs smooth [Rhus glabra] 63. Milky sap absent. 66. Leaf scars completely encircling the bud [Cladrastis lutea] 66. Leaf scars only partly encircling the bud [Ptelea trifoliata] 54. Buds with 1 or more scales. 67. Buds with 1 scale [Salix spp.] 67. Buds with 2 or more scales. 68. Bundle scar 1. 69. Twigs with short spur-like shoots [Ilex decidua] 69. Twigs without short spur-like shoots [Diospyros virginiana] 68. Bundle scars 2 or more. 70. Buds at least 4 times longer than broad. 71. Stipular scars encircling the twig, or nearly so [Fagus grandifolia] 71. Stipular scars not encircling the twigs, or absent. 72. Lowermost bud scale directly above the leaf scar [Populus deltoides] 72. Lowermost bud scale to one side of leaf scar. 73. Twigs reddish-brown, with pale lenticels [Amelanchier arborea] 73. Twigs gray-brown, with dark lenticels [Amelanchier laevis] 70. Buds less than 4 times longer than broad. (Go to 74) 74. Pith star-shaped, or triangular, or variously lobed in cross-section. 75. Lowermost bud scale directly above the leaf scar. 76. Twigs densely hairy; bark white [Populus alba] 76. Twigs smooth or sparsely hairy. 77. Visible bud scales more than 4. 78. Buds smooth, shiny, brown [Populus tremuloides] 78. Buds hairy, dull, gray [Populus grandidentata] 77. Visible bud scales 3-4. 79. Buds at least ½ inch long [Populus deltoides] 79. Buds less than ½ inch long [Populus heterophylla] 75. Lowermost bud scale to one side of leaf scar. 80. Buds clustered near the tip of the twig; bud scales in 5 rows. 81. Buds at least ¼ inch long. 82. Buds angular. 83. Buds smooth [Quercus shumardii] 83. Buds hairy, at least at tip. 84. Buds hairy all over. 85. Buds with rusty or brown hairs. 86. Buds with rusty hairs [Quercus marilandica] 86. Buds with brown hairs [Quercus michauxii] 85. Buds with gray hairs [Quercus velutina] 84. Buds hairy only at the tip. 87. Buds light red-brown [Quercus pagodaefolia] 87. Buds dark red-brown [Quercus coccinea] 82. Buds not angular. 88. Buds and twigs orange-brown [Quercus prinus] 88. Buds and twigs red, red-brown, dark brown, or gray-brown. 89. Buds red or red-brown. 90. Buds light red to light red-brown [Quercus rubra] 90. Buds dark red to dark red-brown [Quercus falcata] 89. Buds dark brown [Quercus coccinea] 81. Buds less than ¼ inch long. 91. Buds pointed at the tip. 92. Buds and twigs brown to orange-brown [Quercus muhlenbergii] 92. Buds and twigs red to red-brown to gray-brown. 93. Scales of buds hairy. 94. Twigs dark red-brown to gray; buds red-brown [Quercus falcata] 94. Twigs light or dark brown; buds gray-brown [Quercus imbricaria] 93. Scales of buds smooth or nearly so. 95. Buds dark red-brown [Quercus phellos] 95. Buds light red-brown [Quercus palustris] 91. Buds more or less rounded. 96. Twigs red-brown, shiny. 97. Buds not angular [Quercus alba] 97. Buds angular [Quercus ellipsoidalis] 96. Twigs gray to yellow-brown to purplish, dull. 98. Twigs and buds smooth or nearly so. 99. Twigs purplish, with a whitish coating [Quercus bicolor] 99. Twigs gray to yellow-brown [Quercus lyrata] 98. Twigs and buds hairy. 100. Buds red-brown [Quercus stellata] 100. Buds gray to gray-brown [Quercus macrocarpa] 80. Buds not clustered near the tip of the twig; bud scales not in 5 rows. 101. Bundle scars in more than 3 groups; leaf scars lobed. 102. Visible bud scales 2. 103. Buds bright yellow [Carya cordiformis] 103. Bud scales brown or reddish-brown. 104. Terminal bud up to ½ inch long; twigs with orange lenticels [Carya illinoensis] 104. Terminal bud up to ¼ inch long; twigs with pale lenticels [Carya aquatica] 102. Visible bud scales more than 2. 105. Some or all the terminal buds ½ inch long or longer. 106. Outermost bud scales falling away early, revealing pale inner scales; bark not peeling [Carya tomentosa] 106. Outermost bud scales persistent; bark peeling. 107. Twigs orange-brown, with orange lenticels [Carya laciniosa] 107. Twigs dark brown or red-brown, with pale lenticels [Carya ovata] 105. Terminal buds usually less than ½ inch long. 108. Buds rusty-hairy, with silvery or yellow scales [Carya texana] 108. Buds smooth or only slightly hairy, without scales. 109. Bark smooth or furrowed, not scaly [Carya glabra] 109. Bark becoming scaly [Carya ovalis] 101. Bundle scars in 3 groups; leaf scars not lobed. 110. Buds up to ⅙ inch long; twigs bitter to the taste. 111. Pith triangular in cross-section [Alnus glutinosa] 111. Pith not triangular in cross section. 112. Buds very shiny [Prunus serotina] 112. Buds dull [Prunus virginiana] 110. Buds longer than ⅙ inch; twigs not bitter to the taste. 113. Twigs sometimes with corky wings; buds with 4 or more exposed scales [Liquidambar styraciflua] 113. Twigs without corky wings; buds with 2-3 exposed scales [Castanea dentata] 74. Pith round or nearly so in cross-section. 114. Terminal bud present. 115. Buds with 2-3 exposed scales [Cornus alternifolia] 115. Buds with 4 or more exposed scales. 116. Bud scales fleshy [Crataegus spp.]. 116. Bud scales not fleshy [Prunus spp.] 114. Terminal bud absent. 117. Leaf scars at least ½ inch across; bundle scars 9 [Ailanthus altissima] 117. Leaf scars smaller; bundle scars not 9. 118. Stipular scars absent. 119. Leaf scars bordered by hairs [Cercis canadensis] 119. Leaf scars not hairy [Gleditsia spp.] 118. Stipular scars present. 120. Exposed bud scales 2. 121. Milky sap present [Broussonetia papyrifera] 121. Milky sap absent. 122. Twigs gray or brown [Tilia americana] 122. Twigs light red [Tilia heterophylla] 120. Exposed bud scales 3 or more. 123. Exposed bud scales 3-4; lenticels horizontal. 124. Twigs with taste of wintergreen [Betula lutea] 124. Twigs without taste of wintergreen. 125. Twigs and buds smooth; bark white [Betula papyrifera] 125. Twigs and buds somewhat hairy; bark reddish [Betula nigra] 123. Exposed bud scales more than 4; lenticels more or less circular. 126. Bundle scars not in groups of 3; milky sap present. 127. Buds about ¼ inch long [Morus rubra] 127. Buds about ⅛ inch long [Morus alba] 126. Bundle scars in groups of 3; milky sap absent. 128. Exposed bud scales usually about 12 [Carpinus caroliniana] 128. Exposed bud scales usually about 6. 129. Leaf scars and bundle scars slightly elevated [Ostrya virginiana] 129. Leaf scars and bundle scars depressed. 130. Buds less than ⅛ inch long [Ulmus pumila] 130. Buds at least ⅛ inch long. 131. Some of the twigs with corky wings. 132. Buds about ¼ inch long [Ulmus thomasii] 132. Buds about ⅛ inch long [Ulmus alata] 131. None of the twigs with corky wings. 133. Buds rusty-hairy, about ¼ inch long [Ulmus rubra] 133. Buds light brown, smooth, about ⅛ inch long [Ulmus americana]

Trees of Illinois

SOUTHERN SUGAR MAPLE
Acer barbatum Michx.

Growth Form: Medium tree up to 60 feet tall; trunk diameter up to 2 feet; crown rounded.

Bark: Smooth and pale brown at first, becoming darker and furrowed when old.

Twigs: Slender, brown, smooth or hairy, usually with pale lenticels; leaf scars opposite, U-shaped, with 3-7 bundle traces.

Buds: Rounded, reddish-brown, hairy, up to ¼ inch long.

Leaves: Opposite, simple; blades up to 4 inches long, nearly as broad, palmately 3- to 5-lobed, drooping on the sides, the edges sparsely and coarsely toothed, green and smooth or a little hairy on the upper surface, paler and much hairier on the lower surface; leaf-stalks up to 3 inches long, very hairy. The leaves turn yellow or orange in the autumn.

Flowers: Staminate and pistillate borne separately, but sometimes on the same tree, in dense clusters, yellowish-green, appearing as the leaves unfold.

Fruit: Borne in pairs, composed of a wing with a seed at the base, greenish, up to 1 inch long.

Wood: Heavy, strong, coarse-grained, light brown.

Uses: Furniture, interior finishing, cabinets.

Habitat: Woodlands.

Range: Virginia across southern Illinois to southeastern Oklahoma, south to Texas, east to Florida.

Distinguishing Features: The Southern Sugar Maple resembles the Black Maple because of its drooping leaves, but differs by its smaller, thicker leaves.

BOX ELDER
Acer negundo L.

Other Name: Ash-leaved Maple.

Growth Form: Medium tree up to 60 feet tall; trunk diameter up to 4 feet; crown wide-spreading.

Bark: Light brown, ridged when young, becoming deeply furrowed with age.

Twigs: Smooth, green, glaucous, or rarely purplish, shiny, usually with white lenticels; leaf scars opposite, U-shaped, with 5-9 bundle traces.

Buds: Rounded, white-hairy, up to ⅛ inch long.

Leaves: Opposite, pinnately compound, with 3-7 leaflets; leaflets elliptic to ovate, up to 4 inches long, about half as broad, pointed at the tip, tapering or rounded at the sometimes asymmetrical base, smooth or usually coarsely toothed along the edges or even shallowly lobed, light green and smooth on the upper surface, paler and smooth or hairy on the lower surface.

Flowers: Staminate and pistillate borne on separate trees, several in a cluster, greenish-yellow, appearing as the leaves begin to unfold.

Fruit: Borne in pairs, in drooping clusters, composed of a curved wing with a seed at the base, greenish-yellow, up to 2 inches long.

Wood: Light weight, soft, close-grained, white.

Uses: Paper pulp, interior finishing, furniture.

Habitat: Moist woods.

Range: Vermont across to Saskatchewan, south to Texas, east to Florida.

Distinguishing Features: The Box Elder most nearly resembles ashes, but differs by its green or glaucous twigs and its paired fruits.

BLACK MAPLE
Acer nigrum Michx.

Growth Form: Medium tree up to 65 feet tall; trunk diameter up to 2½ feet; crown broad, with several upright branches.

Bark: Dark brown to black, smooth when young, soon becoming furrowed and scaly.

Twigs: Slender, brown, smooth, often with pale lenticels; leaf scars opposite, U-shaped, with 3-7 bundle traces.

Buds: Pointed, dark brown, finely hairy, up to one-fourth inch long.

Leaves: Opposite, simple; blades up to 6 inches long and nearly as broad, palmately 3- to 5-lobed, drooping on the sides, the edges of the leaves sparsely and coarsely toothed, green and smooth on the upper surface, yellow-green and smooth or hairy on the veins on the lower surface; leafstalks up to 5 inches long, smooth or hairy. The leaves turn yellow in the autumn.

Flowers: Staminate and pistillate borne separately, but sometimes on the same tree, in dense clusters, yellowish, appearing as the leaves unfold.

Fruit: Borne in pairs, composed of a wing with a seed at the base, reddish-brown to greenish, up to 1 inch long.

Wood: Heavy, strong, coarse-grained, brown.

Uses: Furniture, cabinets.

Habitat: Rich woodlands.

Range: New Hampshire across to Minnesota and South Dakota, south to Louisiana, east to Georgia.

Distinguishing Features: The Black Maple is distinguished from the Sugar Maple by its drooping leaves. It differs from the Southern Sugar Maple, which also has drooping leaves, by its larger, thinner leaves.

RED MAPLE
Acer rubrum L.

Growth Form: Medium tree up to 70 feet tall; trunk diameter up to 3 feet; crown oval or rounded.

Bark: Gray and smooth when young, becoming darker and scaly.

Twigs: Slender, mostly smooth, more or less reddish, usually with pale lenticels; leaf scars opposite, U-shaped, with 3-7 bundle traces.

Buds: Rounded, reddish, usually hairy, up to ¼ inch long.

Leaves: Opposite, simple; blades up to 6 inches long, nearly as broad, palmately 3- to 5-lobed, the edges of the leaves sharply toothed to nearly toothless, pale green and smooth on the upper surface, white or gray and either smooth or hairy on the lower surface; leafstalks smooth or finely hairy, up to 4 inches long.

Flowers: Staminate and pistillate borne separately, but sometimes on the same tree, in dense clusters, bright red or yellow, opening in February and March before the leaves begin to unfold.

Fruit: Borne in pairs, composed of an erect wing with a seed at the base, red or yellow, up to 1 inch long.

Wood: Heavy, close-grained, light brown.

Uses: Furniture, gun-stocks.

Habitat: Swamps, low woods, upland slopes, bluff tops.

Range: Newfoundland across to Ontario, south to eastern Texas, east to Florida.

Distinguishing Features: The Red Maple is characterized by its white lower leaf surfaces and its shallowly lobed leaves. The similar Silver Maple has very deeply lobed leaves.

SWAMP RED MAPLE
rubrum L. var. drummondii (H. & A.) Sarg.

Growth Form: Medium tree up to 40 feet tall; trunk diameter up to 1 foot; crown narrow.

Bark: Gray and smooth when young, becoming darker and scaly.

Twigs: Slender, white-hairy when young, usually becoming smooth or nearly so, reddish; leaf scars opposite, U-shaped, with 3-7 bundle traces.

Buds: Rounded, reddish, hairy, up to ¼ inch long.

Leaves: Opposite, simple; blades up to 6 inches long, nearly as broad, palmately 3- to 5-lobed, the edges of the leaves toothed, green and somewhat hairy on the upper surface, densely white-hairy on the lower surface; leafstalks stout, densely hairy, up to 4 inches long.

Flowers: Staminate and pistillate borne separately, but sometimes on the same tree, in dense red clusters, opening before the leaves begin to unfold.

Fruit: Borne in pairs, composed of an erect wing with a seed at the base, bright red, over 1 inch long.

Wood: Heavy, coarse-grained, light brown.

Use: Furniture.

Habitat: Wooded swamps.

Range: New Jersey across to Missouri, south to Texas, east to Florida.

Distinguishing Features: The Swamp Red Maple is distinguished from the Red Maple by the dense coat of white hairs on the undersurface of the leaves and by the longer fruits.

SILVER MAPLE
Acer saccharinum L.

Other Name: Soft Maple.

Growth Form: Medium to large tree up to 100 feet tall; trunk diameter up to 5 feet; crown usually broadly rounded.

Bark: Gray or silvery, smooth at first, becoming loose and scaly or even somewhat shaggy when old.

Twigs: Slender, reddish-brown, smooth, often curving upward; leaf scars opposite, U-shaped, with 3-7 bundle traces.

Buds: More or less rounded, reddish-brown, smooth to finely hairy, up to ⅛ inch long.

Leaves: Opposite, simple; blades up to 8 inches long, nearly as broad, deeply palmately 5-lobed, the edges of the leaves sharply toothed, pale green and smooth on the upper surface, silvery-white and usually smooth on the lower surface, except in the leaf axils; leafstalks smooth, up to 5 inches long, often reddish.

Flowers: Staminate and pistillate borne separately, but sometimes on the same tree, in dense clusters, greenish-yellow, opening in February and March before the leaves begin to unfold.

Fruit: Borne in pairs, composed of a curved wing with a seed at the base, green or yellow, up to 3 inches long.

Wood: Hard, close-grained, pale brown.

Uses: Furniture; sometimes grown as an ornamental, but the branchlets are brittle.

Habitat: Wet soil.

Range: New Brunswick across to Minnesota and South Dakota, south to Oklahoma, Texas, east to northern Florida.

Distinguishing Features: The deeply lobed leaves which are silvery-white on the flower surface best distinguish this tree.

SUGAR MAPLE
Acer saccharum Marsh.

Other Name: Hard Maple.

Growth Form: Medium to large tree up to 80 feet tall; trunk diameter up to 3 feet; crown broadly rounded, with many branches.

Bark: Gray to dark brown to black, becoming furrowed and scaly.

Twigs: Slender, smooth, brown, often with pale lenticels; leaf scars opposite, U-shaped, with 3-7 bundle traces.

Buds: Pointed, dark brown, smooth or a little hairy, shiny, up to ¼ inch long.

Leaves: Opposite, simple; blades up to 5 inches long, nearly as broad or a little broader, palmately 3- to 5-lobed, the edges of the leaves sparsely and coarsely toothed, dark green and smooth on the upper surface, green or paler on the lower surface and usually smooth, or sometimes hairy on the veins; leafstalks up to 3 inches long, smooth and sometimes hairy. The leaves turn brilliant shades of yellow and orange in the autumn.

Flowers: Staminate and pistillate borne separately, but sometimes on the same tree, in dense clusters, greenish-yellow, appearing as the leaves begin to unfold.

Fruit: Borne in pairs, composed of a wing with a seed at the base, greenish-yellow to brownish, up to 1 inch long.

Wood: Heavy, strong, close-grained, light brown.

Uses: Furniture, interior finishing, cabinets; maple sugar is derived from the sap; frequently grown as an ornamental.

Habitat: Moist woods.

Range: Newfoundland across to Manitoba, south to eastern Texas, east to northern Florida.

Distinguishing Features: Leaves of the Sugar Maple differ from those of the Black Maple and the Southern Sugar Maple by being flat, rather than drooping along the edges. {Sap differs from the Norway Maple, Acer platanoides, by being clear rather than milky.}

RED BUCKEYE
Aesculus discolor Pursh

Growth Form: Small tree to 25 feet tall; trunk diameter up to 10 inches; crown rounded and spreading.

Bark: Gray to tan, smooth.

Twigs: Rather stout, gray to tan, smooth; leaf scars opposite, triangular, with 3 groups of bundle traces.

Buds: Ovoid, pointed, reddish-brown, up to ½ inch long, not hairy, not sticky.

Leaves: Opposite, palmately compound, with 5 leaflets; leaflets elliptic to obovate, pointed at the tip, tapering to the base, up to 6 inches long, less than half as wide, toothed along the edges, green and smooth on the upper surface, paler and finely hairy on the lower surface.

Flowers: Numerous, red, in large clusters sometimes nearly 1 foot long, appearing in April.

Fruit: Spherical or punching-bag shaped, up to 2 inches across, light brown, not prickly, containing 1 or 2 light reddish-brown seeds.

Wood: Soft, close-grained, light in weight, pale brown.

Use: Sometimes grown as an ornamental because of its showy flowers.

Habitat: Rich woods.

Range: North Carolina across to Missouri, south to Texas, east to Georgia.

Distinguishing Features: The smooth fruits and the beautiful red flowers distinguish this species from other members of the genus in Illinois.

OHIO BUCKEYE
Aesculus glabra Willd.

Growth Form: Medium tree to 55 feet tall; trunk diameter up to 15 inches; crown broadly rounded.

Bark: Gray to pale gray, deeply furrowed and roughened when mature.

Twigs: Stout, pale brown, smooth; leaf scars opposite, triangular, with 3 groups of bundle traces.

Buds: Ovoid, pointed, reddish-brown to yellowish, up to ⅔ inch long, not hairy, not sticky.

Leaves: Opposite, palmately compound, with 5 or 7 leaflets; leaflets obovate to oblanceolate, long-pointed at the tip, tapering to the base, up to 6 inches long, less than half as wide, toothed along the edges, green and smooth on the upper surface, green or much whitened on the lower surface.

Flowers: Numerous, yellow-green, in large clusters sometimes nearly 1 foot long, appearing in April and May, the petals of each flower of different lengths.

Fruit: Prickly, spherical or nearly so, up to 1½ inch in diameter, pale brown, containing 1 large, smooth and shiny seed.

Wood: Soft, close-grained, light in weight, pale brown to nearly white.

Uses: Paper pulp. The tree is also sometimes grown as an ornamental.

Habitat: Usually rich woods.

Range: Pennsylvania across to Nebraska, south to Oklahoma, east to Alabama.

Distinguishing Features: The Ohio Buckeye differs from the Horse Chestnut {Aesculus hippocastanum} by its non-sticky buds. It differs from the Red Buckeye by the greenish-yellow flowers and prickly fruits.

TREE-OF-HEAVEN
Ailanthus altissima (Mill.) Swingle

Growth Form: Medium to large tree to 75 feet tall; trunk diameter up to 2 feet; crown spreading and irregular. The tree readily spreads by underground root-suckers.

Bark: Smooth or slightly roughened, light brown to dark brown.

Twigs: Stout, angular, smooth, gray to light brown, with lenticels; leaf scars alternate, large, broadly heart-shaped, slightly elevated, with usually 9 bundle traces.

Buds: Rounded, up to ⅛ inch in diameter, smooth or a little hairy, brown.

Leaves: Alternate, pinnately compound, with up to 41 leaflets; leaflets lanceolate, tapering to a long point at the tip, rounded at the base, up to 6 inches long, less than half as wide, smooth or somewhat hairy on both surfaces, often with some teeth along the edges. The leaves have an unpleasant odor when crushed.

Flowers: Some flowers with both stamens and pistils, others with one or the other, in large green or yellow clusters, each flower small, with 5 petals. The staminate flowers produce a very unpleasant odor. The flowers appear in June and July.

Fruit: Large clusters of winged seeds, yellow or orange, each fruit up to 2 inches long with one seed about in the middle.

Use: Tree-of-Heaven is grown as an ornamental, principally in urban areas where it is able to withstand considerable smoke and smog.

Habitat: Disturbed woods; readily adapts to urban conditions.

Range: Native of Asia; frequently planted in the United States and readily spreading from cultivation.

Distinguishing Features: The pinnately compound leaves with up to 41 leaflets, unpleasantly scented when crushed, make this a readily recognizable species.

BLACK ALDER
Alnus glutinosa (L.) Gaertn.

Growth Form: Small or medium tree to 45 feet tall; trunk diameter up to 12 inches; crown broadly rounded when mature.

Bark: Smooth at first, becoming shallowly fissured with age.

Twigs: Slender, gray or gray-brown, smooth; leaf scars alternate, with 3 bundle traces.

Leaves: Alternate, simple; blades nearly round or obovate, rounded at the tip, rounded or somewhat tapering to the base, up to five inches long, often nearly as broad, irregularly and rather coarsely toothed along the edges, dark green and smooth on the upper surface, green and smooth beneath, or sometimes hairy on the veins; leafstalks stout, up to 1 inch long, usually smooth.

Flowers: Staminate and pistillate flowers borne separately but on the same tree, appearing before the leaves unfold, the staminate in slender, drooping catkins up to 3 inches long, the pistillate in erect, oblong “cones” less than 1 inch long.

Fruit: Cone-shaped, up to ¾ inch long, composed of several nut-like seeds, each subtended by a woody segment of the “cone.”

Wood: Soft, straight-grained.

Uses: The wood is easily carved and used in the making of small wooden objects. It is also used for charcoal and fuel. The bark has reputed medicinal properties.

Habitat: Moist, disturbed areas.

Range: Native of Europe, Asia, and Africa; naturalized throughout much of northeastern North America.

Distinguishing Features: The small, woody “cones” and the often orbicular, irregularly toothed leaves are the distinguishing marks of this species.

SHADBUSH
Amelanchier arborea (Michx. f.) Fern.

Other Names: Shadblow; Serviceberry.

Growth Form: Small tree up to 20 feet tall; trunk diameter up to 8 inches; crown rounded and spreading with many slender branchlets; trunk straight, slender, often divided into several trunks.

Bark: Smooth and silvery at first, later becoming darker and divided into loose scales.

Twigs: Slender, brown, with a few hairs when very young; leaf scars alternate, 2-ranked, slightly elevated, narrowly crescent-shaped, with 3 bundle traces.

Buds: Pointed, slender, brown, up to ½ inch long.

Leaves: Alternate, simple; blades oval to broadly lanceolate, pointed at the tip, rounded or sometimes a little heart-shaped at the base, finely toothed along the edges, green and smooth or nearly so on the upper surface, paler and often hairy on the lower surface, up to 4 inches long and about half as broad; leafstalks up to 2 inches long, smooth or hairy.

Flowers: Several produced in drooping clusters before the leaves appear, each showy with 5 white, oblong petals, with much of the flower hairy.

Fruit: Mostly spherical, up to ¼ inch in diameter, reddish-purple, capped by the persistent calyx, dry, 1- to 2-seeded.

Wood: Rather heavy, hard, close-grained, reddish-brown.

Uses: Fuel, tool handles; the fruit is edible.

Habitat: Wooded slopes; edge of cliffs.

Range: Quebec across to Minnesota, south to Nebraska, east to Louisiana and Florida.

Distinguishing Features: The Shadbush is recognized by its alternate, simple leaves which are usually heart-shaped at the base, and by its distinctive white flowers.

SMOOTH SHADBUSH
Amelanchier laevis Wieg.

Other Name: Smooth Serviceberry.

Growth Form: Small tree up to 15 feet tall; trunk diameter up to 6 inches; crown narrowly round-topped, with many slender branchlets.

Bark: Smooth and gray at first, becoming darker and scaly at maturity.

Twigs: Slender, reddish-brown or grayish, smooth; leaf scars alternate, slightly elevated, narrowly crescent-shaped, with 3 bundle traces.

Buds: Slender, pointed, reddish-brown, smooth, up to ¾ inch long.

Leaves: Alternate, simple; blades elliptic to ovate, pointed at the tip, usually rounded at the base, up to 3 inches long, about ½ as broad, finely toothed along the edges, green and smooth on the upper surface, paler and smooth on the lower surface; leafstalks slender, up to 1 inch long, smooth.

Flowers: Up to 6 in drooping clusters, appearing after the leaves are half grown, each showy with 5 white, narrow petals, with most of the flower smooth.

Fruit: Usually spherical, up to ¼ inch in diameter, dark purple, sweet, fleshy, 1- to 2-seeded.

Wood: Hard, heavy, close-grained, dark brown.

Uses: Fuel, tool handles; the fruits are edible.

Habitat: Moist woods and slopes.

Range: Newfoundland across to Ontario, south to Iowa, Illinois, and Georgia.

Distinguishing Features: The Smooth Shadbush differs from the Shadbush by its smooth leafstalks and juicy, edible, dark purple fruits.

HERCULES’ CLUB
Aralia spinosa L.

Other Name: Devil’s Walking-stick.

Growth Form: Small tree to 30 feet tall; trunk diameter up to 6 inches; crown widely spreading.

Bark: Dark brown, roughened, shallowly furrowed, with short, hard prickles.

Twigs: Stout, pale brown or gray, smooth except for many short, hard prickles; leaf scars alternate, broadly U-shaped, with about 15 bundle traces.

Buds: Cone-shaped, brown, smooth, up to ½ inch long.

Leaves: Alternate, doubly or triply pinnately compound, with very numerous leaflets; leaflets ovate to lance-ovate, pointed at the tip, tapering to rounded at the base, up to 3 inches long, about half as wide, coarsely toothed along the edges, green and smooth on the upper surface, paler and smooth on the lower surface, except usually for a few prickles along the veins.

Flowers: Numerous, in many umbrella-shaped clusters, appearing during late June and July, each with 5 small white petals and purple stalks.

Fruit: Black, spherical berries up to ⅛ inch in diameter, containing 2-5 seeds.

Wood: Light in weight, soft, brittle, close-grained, pale brown.

Use: Hercules’ Club is sometimes grown as an ornamental.

Habitat: Rich woods.

Range: New Jersey across to Iowa, south to Texas, east to Florida.

Distinguishing Features: The clusters of flowers and the leaves each may be as much as 4 feet long. The short, sharp prickles of the twigs are distinctive.

PAWPAW
Asimina triloba Dunal.

Growth Form: Small tree rarely up to 40 feet tall; trunk diameter up to 10 inches; crown broad and spreading; trunk straight, slender; thickets develop by means of root suckers.

Bark: Dark brown, thin, smooth at first, becoming shallowly fissured with age.

Twigs: Slender, smooth, gray; leaf scars alternate, 2-ranked, more or less horseshoe-shaped, usually with 5 or less commonly 7 bundle traces.

Buds: Very narrow, dark rusty-brown, covered with golden hairs, up to ⅔ inch long, without bud scales.

Leaves: Alternate, simple; blades broadly lance-shaped to elliptic, short-pointed at the tip, narrowed to the base, without teeth along the edges, smooth on both surfaces, paler on the lower surface, up to 1 foot long and 6 inches broad; leafstalks short, slender, smooth.

Flowers: Borne singly when the leaves begin to unfold, up to 2 inches across, green at first, becoming deep maroon, composed of three wrinkled, leathery sepals and six similar petals.

Fruit: Oblong, thick, up to 6 inches long, greenish-yellow, with yellow edible flesh and several dark brown seeds, ripening in September.

Wood: Soft, coarse-grained, light in weight, greenish-yellow.

Use: The fruit is used as a source of food; the wood has few uses.

Habitat: Woods and thickets, often many growing together in a colony.

Range: New York across to Michigan and Iowa, south to Texas, east to Florida.

Distinguishing Features: Pawpaw is distinguished by its large, toothless, alternate leaves, its slender buds without bud scales, and its thick, fleshy fruits.

YELLOW BIRCH
Betula lutea Michx.

Other Name: Gray Birch.

Growth Form: Moderate tree up to 50 feet tall; trunk diameter up to 1½ feet; crown broadly rounded, with small branches.

Bark: Smooth and silvery or grayish, curling into strips, very rough when old.

Twigs: Slender, greenish-brown, smooth, with numerous lenticels; leaf scars alternate, half-elliptical, with 3 bundle traces.

Buds: Pointed, brown, usually somewhat hairy, up to ⅙ inch long.

Leaves: Alternate, simple; blades ovate, pointed at the tip, more or less rounded at the somewhat asymmetrical base, up to 5 inches long, and nearly half as wide, double-toothed, dark green and nearly smooth on the upper surface, paler and usually somewhat hairy on the lower surface; leafstalks yellow, hairy, up to one inch long. The leaves turn yellow in the autumn.

Flowers: Staminate and pistillate flowers borne separately but on the same tree, the staminate crowded in elongated clusters, the pistillate crowded in shorter, thicker clusters, appearing after the leaves have begun to unfold.

Fruit: Several winged nuts, crowded together in erect “cones” up to 1½ inches long.

Wood: Heavy, hard, strong, pale brown.

Uses: Furniture, flooring, boxes.

Habitat: Wooded slopes.

Range: Newfoundland across to Manitoba, south to Iowa, northern Illinois, northern Indiana, Ohio, and Delaware; also in the Appalachian Mountains to Georgia.

Distinguishing Features: The Yellow Birch differs from all other birches in Illinois by its silvery or grayish bark and its ovate leaves. The bark has the faint fragrance of wintergreen.

RIVER BIRCH
Betula nigra L.

Other Name: Red Birch.

Growth Form: Up to 75 feet tall; trunk diameter up to 2 feet; crown irregularly rounded.

Bark: Curling, shredding, brownish-pink to reddish-brown.

Twigs: Slender, reddish-brown, with several short hairs; leaf scars alternate, half-elliptical, with 3 bundle traces.

Buds: Up to one-fourth inch long, pointed, hairy.

Leaves: Alternate, simple; blades rhombic to ovate, coarsely doubly toothed, paler and densely hairy on the lower surface, up to 3 inches long, acute at the tip, truncate or tapering to the base, the leafstalks woolly.

Flowers: Staminate and pistillate on same tree, inconspicuous, opening in late April and May, the staminate in slender drooping clusters, the pistillate in short, conelike, woolly clusters.

Fruit: Tiny, hairy nuts, each with a 3-lobed wing, crowded together in a cylindrical cone up to 1½ inches long and ½ inch thick.

Wood: Strong but light, pale brown.

Uses: Wood is used for furniture; sometimes planted as an ornamental.

Habitat: Along rivers and streams; bottomland woods.

Range: Massachusetts and New Hampshire across to southern Minnesota and eastern Kansas, south to eastern Texas and Florida.

Distinguishing Features: The shaggy, peeling reddish-brown bark readily distinguishes this tree from any other in Illinois, as does its rhombic, doubly toothed leaves.