Using a Dichotomous key to identify unknown trees.
A dichotomous key is a series of paired statements. At each step, you must look closely at the trees characteristics to see which of the two statements (choices) is true of the tree you are trying to identify. After choosing the correct statement concerning your tree, you are directed to another pair of choices and the process continues until you arrive at the correct name for the tree.
Key to native trees of Middle Tennessee:
1 Leaves narrow, needle-like, or scalelike; reproductive structures are cones in most of these except one which
produces berry-like reproductive bodies........................................................................................ ........................2
1 Leaves broad, blade-like; fruits not cones ....... ....................5
2 Leaves like needles, much longer than wide ....... ......................3
2 Leaves scale-like (shaped like little triangles); "fruit" is light blue and berry-like.........................................................
...............................................................................................................Juniperus virginiana Eastern Red Cedar
3 Needle-like leaves in clusters ...... ............ ..............Pinus (Pines)
3 Needles attach to the stem singly ...... ........... ........4
4 Needles yellow-green, in branchlets and fall off in autumn (deciduous); the small cone is spherical.............................. .................................... ...Taxodium distichum (Bald Cypress)
4 Needles dark-green, not in branchlets, not deciduous; cone small and elongate ........................Tsuga candadensis
Eastern Hemlock)
5 Twigs with thorns, spines, or prickles.......................................................................................................................6
5 Twigs without thorns, spines or prickles.................................................................................................................10
6 Leaves simple (leaf not divided into leaflets).............................................................................................................7
6 Leaves compound (leaf is divided into leaflets).........................................................................................................9
7 Leaf margin entire (smooth, no teeth), twigs exude milky sap when cut...........................................Maclura pomifera
(Osage Orange, Hedge Apple)
7 Leaf margin toothed and/or lobed; no milky sap.......................................................................................................8
8 Leaves often lobed, long sharp thorns...................................................................................Crataegus (Hawthorns)
8 Leaves not lobed, fine teeth, thorns blunt, leaf stalks with glands on upper surface, small trees.........................Prunus
(Wild Plums)
9 Leaves once pinnately compound, leaflets odd-numbered, thorns short and not branched........Robinia pseudoacacia
(Black Locust)
9 Leaves twice pinnately compound, leaflets even-numbered, thorns large and branched..............Gleditsia triacanthos
10 Leaves opposite (two at a node) or whorled (three at a node) on the stem...............................................................11
10 Leaves alternate on the stem...................................................................................................................................17
11 Heart-shaped leaves whorled (3 per node); fruits long slender pods.................................................Catalpa speciosa
11 Leaves opposite.....................................................................................................................................................12
12 Leaves simple, not divided into leaflets....................................................................................................................13
12 Leaves compound (each leaf divided into smaller leaflets)........................................................................................15
13 Leaves palmately lobed and veined......................................................................................................Acer (Maples).
13 Leaves entire or toothed but not lobed............................................................................................................14
14 Leaves toothed......................................................................................................................Viburnum (Viburnums)
14 Leaves entire; pinnate veins incurve toward leaf apex..................................................................Cornus (Dogwoods)
15 Leaves palmately compound (five leaflets radiate from a common point on leaf stalk)..................Aesculus (Buckeyes)
15 Leaves pinnately compound (leaflets attach in such a way to give the leaf a featherlike appearance).........................16
16 Leaflets 3-5, coarsely toothed...........................................................................................Acer negundo (Box Elder)
16 Leaflets more than 5......................................................................................................................Fraxinus (Ashes)
17 Leaves compound................................................................................................................................................18
17 Leaves simple.......................................................................................................................................................22
18 Twigs hairy with pith (core of twig) that is chambered (cut twig lengthwise to examine pith)...............Juglans (Walnuts)
18 Pith of twigs not chambered...................................................................................................................................19
19 Swollen base of petiole (leaf stalk) conceals axillary (lateral) bud; fruit a legume pod................................................20
19 Base of petiole does not conceal lateral bud...........................................................................................................21
20 Leaflets opposite; bark deeply furrowed.........................................................Robinia pseudoacacia (Black Locust)
20 Leaflets alternate; gray bark is smooth .....................................................................Cladrastis lutea (Yellowwood)
21 Leaves once pinnately compound; fruit a nut................................................................................Carya (Hickories)
21 Leaves very large, twice pinnately compound; fruit a large flat pod.....Gymnocladus dioicus (Kentucky Coffee Tree)
22 Leaves entire (leaf margin is smooth, no teeth or lobes)..........................................................................................23
22 Leaves toothed and/or lobed.................................................................................................................................28
23 Leaves heart-shaped, fruit a small legume pod.............................................................Cercis canadensis (Red Bud)
23 Leaves not heart-shaped; fruit not a legume pod....................................................................................................24
24 Leaves 20 cm or longer.........................................................................................................................................25
24 Leaves mostly less than 15 cm...............................................................................................................................26
25 Scars encircling twigs at nodes (a node is where a leaf stalk attaches to the twig); rare...............Magnolia acuminata
(Cucumber Magnolia)
25 No scars encircling twigs at nodes...................................................................................Asimina triloba (Pawpaw)
26 Leaves and buds clustered at stem tips; pith is 5-angled in cross section; fruit an acorn......................Quercus (Oaks)
26 Leaves and buds not clustered at stem tips; pith round in cross section; fruit a drupe or berry..................................27
27 Three small bundle scars on the leaf scar (where leaf stalk had attached to twig); fruit a drupe (fleshy with one seed)...
....................................................................................................................................Nyssa sylvatica (Black Gum)
27 One bundle scar per leaf scar; fruit a berry (fleshy with several seeds inside)..........Diospyros virginiana Persimmon
28 Leaves with teeth (rounded or sharp) along the margin...........................................................................................29
28 Leaves lobed.............................................................................................................................................50
29 Leaf margins with rounded teeth (wavy margin); axillary buds stalked; shrub......Hamamelis virginiana (Witch Hazel)
29 Leaf margins distinctly toothed, buds not stalked; mostly trees................................................................................30
30 Sap milky; fruit berry-like..........................................................................................Morus rubra (Red Mulberry)
30 Sap not milky........................................................................................................................................................31
31 Leaves triangular or heart-shaped, widest at base...................................................................................................32
31 Leaves longer than broad, widest near middle.........................................................................................................33
32 Leaf base asymmetrical, leaves two-ranked; pith circular in cross section........................................Tilia (Basswoods)
32 Leaf base symmetrical; leaves not two-ranked; pith five-angled in cross section...........Populus (Aspen, Cottonwood)
33 Marginal teeth large (2 or fewer per cm of leaf margin)..........................................................................................34
33 Marginal teeth small (3 or more per cm).................................................................................................................39
34 Leaves leathery and evergreen, bearing stout spine-tipped teeth....................................Ilex opaca (American Holly)
34 Leaves not as above.............................................................................................................................................35
35 Leaves and buds clustered at stem tips; fruit an acorn.......................................................................Quercus (Oaks)
35 Leaves and buds not clustered at stem tips; fruit a nut enclosed by a prickly bur.....................................................36
36 Buds long, and sharp-pointed; bark smooth and gray; two 3-angled nuts per bur.............Fagus grandifolia (Beech)
36 Buds short and oval; bark is furrowed in older trees; flattened nuts within a large bur with many long spines............
..................................................................................................................Castanea dentata (American chestnut)
37 Petioles with glands near base of blade........................................................................Prunus (Plums and Cherries)
37 Petioles without glands..........................................................................................................................................38
38 Most leaves at least 3 times longer than broad.......................................................................................................39
38 Leaves less than 3 times as long as broad..............................................................................................................40
39 Buds with one exposed scale.............................................................................................................Salix (Willows)
39 Buds with approximately 6 exposed scales....................................................................Prunus (Plums and Cherries)
40 Leaves 2-ranked (in 2 rows in roughly one plane)................................................................................................. 41
40 Leaves not 2-ranked.............................................................................................................................................47
41 Leaves with 3 main veins from tip of petiole; pith finely chambered at nodes...............Celtis (Hackberry, Sugarberry)
41 Leaves not as above; pith not chambered..............................................................................................................42
42 Main lateral veins don't reach the leaf margin; white flowers early in spring; small edible fruit is ripe in June..............42
............................................................................................................................Amelanchier arborea (Juneberry)
42 Lateral veins extend to leaf margin.........................................................................................................................43
43 Leaf base symmetrical.......................................................................................................................................... 44
43 Leaf base asymmetrical, margin doubly serrate; fruit a samara (dry winged fruit)...................................Ulmus (Elms)
44 Bark smooth, gray; trunk with muscled look; leaves doubly serrate; ...................Carpinus caroliniana (Blue Beech)
44 Trunk not muscled................................................................................................................................................45
45 Some lateral veins forked; bark shredding into narrow vertical strips; fruits are hop-like clusters of nutlets; usually
a small understory tree.........................................................................................Ostrya (Hop Hornbeam or Ironwood)
45 Lateral veins continue to leaf margin not forked.....................................................................................................46
46 Widest part of leaf most often below the middle; bark with large lenticels (pores), often peels horizontally into
papery strips..........................................................................................................................Betula nigra (River Birch)
46 Widest part of leaf near the middle; lenticels inconspicuous; bark furrowed or scaly; not peeling............Ulmus (Elms)
47 Stipules (appendage at base of petiole) or stipule scars present..............................................................................48
47 Stipules and their scars absent; leaves taste sour; leaf margins with very fine teeth......................................................
.............................................................................................................................Oxydendrum arboreum (Sourwood)
48 Petioles with glands near base of blade..........................................................................Prunus (Plums and Cherries)
48 Petioles without glands..........................................................................................................................................49
49 Twig tip delicate, less than 1.5 mm in diameter; leaves finely and regularly toothed; lateral veins don't go all the
way to the leaf margin..................................................................................Amelanchier arboreum (Sourwood)
49 Twig tip stout, more than 1.5 mm. in diameter; fruits are small tart apples.............Pyrus coronaria (Wild Crabapple)
50 Leaves palmately veined and lobed.........................................................................................................................51
50 Leaves pinnately veined and lobed..........................................................................................................................53
51 Sap milky; some leaves lobed, some just toothed......................................................................Morus (Red Mulberry
51 Sap colorless.........................................................................................................................................................52
52 Leaves star-shaped; terminal bud present; twigs often with corky ridges...........Liquidambar styraciflua (Sweetgum)
52 Leaves 3-5 lobed not star-shaped; no terminal bud; twigs do not have corky ridges; stipules or stipule scars at the
nodes;greenish gray and white bark that peels off.....................................................................Platanus (Sycamore)
53 Some leaves unlobed; others with 1 or two lateral lobes; branchlets yellowish green; leaves and bark aromatic............
................................................................................................................................Sassafras albidum (Sassafras)
53 All leaves lobed; branchlets gray to grayish brown; leaves and bark not aromatic....................................................54
54 Leaves mostly 4-lobed, about as broad as long; stipules or stipule scars encircle twigs at nodes...............................
Liriodendron tulipifera (Tulip Poplar)
54 Most leave with 5 or more nodes; leaves longer than broad; no stipules or stipule scars; leaves and buds clustered at
stem tips...............................................................................................................................Quercus (Oaks)