Forest Trees of Illinois (Third Edition)

by Robert H. Mohlenbrock

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]