Key to Illinois Trees in Winter
Reading edition
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
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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.
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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.
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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.
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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.
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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
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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.
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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
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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..
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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.
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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
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