Tree Keys is a tool which may be used to identify plants found in wild and cultivated settings. This resource utilizes visible plant anatomical characteristics which may be viewed during plant dormancy and/or periods of growth. The scope of plants addressed herein is limited primarily to species which may be cultivated successfully in the northeastern United States, but the roster of species is by no means exhaustive. For certain taxa and large genera, it may be advisable to consult specialized reference books.

General Instructions:
Starting at pair number 1, make a series of choices by clicking the appropriate link located to the right (either a number or name). You may Click Here to view more complete tree keys instructions. For assistance with unfamiliar botanical terms used herein, Click Here to visit our glossary.

Page 1: Dichotomous Pairs 1 to 30

1. Leaves persistent and green throughout winter (evergreens). 2
1. Leaves not persistent and green throughout winter (deciduous -- though dead leaves often persistent in the oaks and beeches). 11
2. Leaves broad, with prominent spiny margins. Ilex opaca,
American Holly
2. Leaves narrow, often minute and scale-like; conifers (i.e. cone-bearing trees). 3
3. Leaves mostly needle-shaped and in definite, generally sheathed clusters on the sides of the branches. Pinus sp.,
3. Leaves not in definite clusters. 4
4. Leaves opposite or in 3's, therefore 2 or 3 at a node. 5
4. Leaves alternate, scattered, therefore only 1 at a node. 8
5. Leaves whorled in 3's, all alike, whitened above and green below, awl-shaped, sharp-pointed and spreading; fruit bluish, berry-like; a shrub or low tree. Juniperus communis,
Common Juniper
5. Leaves opposite in 4 ranks, minute, scale-like, closely overlapping. 6
6. Young twigs prominently flattened and forming a flat, 2-ranked, fan-shaped spray often mistaken for the true leaves which are minute and of two shapes, those on edges of twigs being narrower, those on flat sides being broader and more abruptly pointed with each leaf generally showing a conspicuous raised glandular dot; fruit a thin-scaled, oblong, woody cone. Thuja occidentalis,
American Arborvitae
6. Young twigs not prominently flattened; fruit spherical. 7
7. Spray somewhat fan-shaped; young twigs not prominently 4-angled; leaves all alike in shape, some of them with prominent raised glandular dot on the back; fruit a spherical woody cone.

Chamaecyparis thyoides,
Atlantic White Cedar

7. Spray not fan-shaped; young twigs with typical leaves and prominently 4-angled; leaves without conspicuous glandular dots, of two kinds; (a) the juvenile form -- awl-shaped, spiny-pointed and spreading, in 2's or 3's at a node and resembling leaves of Common Juniper, the usual leaf form on young trees but generally to be found on some parts of older trees; (b) the typical form -- smaller, scale-like and closely appressed; fruit bluish, berry-like.

Juniperus virginiana,
Eastern Red Cedar

8. Leaves distinctly flattened. 9
8. Leaves not distinctly flattened, needle-shaped, 4-angled, sitting directly on projections of the stem ("pegs").. Picea sp.,
9. Leaf about 1 cm long with definite leaf-stalk, leaving prominently projecting scar when detached. Tsuga canadensis,
Canadian Hemlock
9. Leaf about 2 cm or more long, without leaf-stalk, leaving a flat or only slightly raised scar when detached. 10
10. Buds small, nearly spherical to broadly ovate, their scales covered and glued together by resinous coating; leaf scars flat. Abies balsamea,
Balsam Fir
10. Buds larger, narrow conical, without resinous coating; leaf-scars slightly raised. Pseudotsuga menziesii,
11. Leaf-scars opposite or in 3's, therefore 2 or 3 at a node. 12
11. Leaf-scars alternate, therefore only 1 at a node. 16
12. Leaf-scars or some of them 3 at a node; bundle-scars in an ellipse; terminal bud absent. Catalpa speciosa,
Northern Catalpa
12. Leaf-scars always 2 at a node; bundle-scars not in an ellipse; terminal bud present. 13
13. Lateral buds, at least the upper ones, covered by persistent bases of leaf-stalks; leaf buds with only a single pair of scales. Cornus florida,
Flowering Dogwood
13. Lateral buds not covered by persistent bases of leaf-stalks; leaf buds with 2 or more pairs of scales. 14
14. Terminal buds large, over 1.5 cm long, sticky or varnished; leaf-scar large, inversely triangular; bundle-scars 3-9, conspicuous. Aesculus hippocastanum,
Common Horsechestnut
14. Terminal buds smaller, under 1.5 cm long, not sticky-varnished, leaf-scars smaller. 15
15. Bundle-scars, minute, numerous in a U-shaped line often more or less confluent; bud-scales scurfy (i.e. rough-downy). Fraxinus sp.,
15. Bundle-scars definitely 3 in number; bud-scales not scurfy. Acer sp.,
16. Stipule-scars entirely encircling the twig. 17
16. Stipule-scars (when present) not encircling the twig. 19
17. Terminal bud absent; (the last lateral bud may appear to be terminal but absence of terminal bud is shown by small scar at end of twig); leaf-scar almost completely surrounding the bud. Platanus occidentalis,
American Planetree
17. Terminal bud present; leaf-scar not surrounding the bud. 18
18. Scar of rudimentary leaf surmounting decurrent ridge on side of bud; buds ovate to conical, hairy at least within. Magnolia sp.,
18. Scars of rudimentary leaf if present at base of bud; buds flattened oblong, smooth without and within. Liriodendron tulipifera,
19. Twigs with thorns, spines or prickles, or branches ending in thorns. 20
19. Twigs without thorns, spines, or prickles. 27
20. Spines in pairs at the nodes, or twigs covered with weak hair-like prickles. 21
20. Spines not in pairs at the nodes, twigs not covered with weak prickles. 22
21. Buds rusty-hairy, more or less covered by bark; terminal bud absent, usually a medium-sized tree.. Robinia pseudoacacia,
Black Locust
21. Buds red, exposed; terminal bud present; a shrub. Zanthoxylum americanum,
22. Thorns lateral, regularly place on the twig at or near the nodes. 23
22. Thorns terminal. 25
23. Thorns generally branched, situated above the nodes; buds several in a longitudinal row, the lower ones covered by the bark. Gleditsia triacanthos,
Common Honeylocust
23. Thorns generally unbranched on twigs, situated at the nodes; sometimes branched thorns on trunk; buds exposed. 24
24. Thorns generally present at all the nodes; bundle-scar single. Maclura pomifera,
Osage Orange
24. Thorns generally absent from many of the nodes; bundle-scars 3. Crataegus sp.,
25. Terminal bud absent, but leaving a terminal scar on twig. Prunus sp.,
25. Terminal bud present, at least on spineless branches. 26
26. Tree with bushy habit of growth; twigs with characteristic licorice-like taste, generally reddish-brown, more or less pale-woolly at least toward apex; lateral buds blunt, flattened, appressed and more or less pale-woolly.

Malus sylvestris,

26. Tree with upright habit of growth; twigs without characteristic taste, generally yellowish green and generally smooth; lateral buds sharp-pointed, smooth or sometimes slightly downy, generally not flattened nor appressed. Pyrus communis,
Common Pear
27. Pith in section lengthwise of twig seen to be interrupted by hollow chambers or by woody partitions. 28
27. Pith continuous; i.e. without hollow chambers or woody partitions. 32
28. Pith chambered, but with chambers confined to the nodes. Carya sp.,
28. Pith chambered, but with chambers not confined to the nodes. 29
29. Pith wide, brown, with hollow chambers; fruit a nut. 30
29. Pith narrow, light colored; fruit a small stone-fruit. 31
30. Downy patch present above leaf-scar; nut elongated. Juglans cinerea,
30. Downy patch absent from leaf-scar; nut round. Juglans nigra,
Black Walnut

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