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Illustrated key of compound-leaved trees

back to main tree key    hickory key          sumac key

(Modified from a text key to common trees of Radnor Lake by W.G. Eickmeier)

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1. Leaves with 3 leaflets, shrubs or small trees:  go to 2

1. Leaves with more than 3 leaflets, may be large trees:  go to 3






2. Leaves opposite and with no strong smell, fruit an inflated baglike capsule:
Staphylea trifolia (American bladdernut)

2. Leaves alternate and having a strong, fragrant smell, fruit a red drupe:
Rhus aromatica (fragrant sumac)






3. Leaves pinnately compound: go to 4

3. Leaves palmately compound:
Aesculus flava (yellow buckeye)






4. Leaves alternate: go to 5

4. Leaves opposite: go to 15






5. Some or all leaves twice compound (bipinnate): go to 6

5. Leaves only once compound: go to 9





6. Trunks or branches with spines or prickles: go to 7

6. Trunks and branches without spines or prickles: go to 8






7. Enormous leaves that are always twice pinnate, leaf petioles usually with prickles, usually a small tree and often a single unbranched stem, prickles relatively short, fruit a purple-black drupe (one-seeded fleshy fruit) in a large terminal panicle:
Aralia spinosa (devil's walking-stick)

7. Leaves may be twice pinnate and once pinnate on the same tree, leaf petioles without prickles, can be a large tree, stout branched thorns often present, legume relatively thin and leathery, about 30 cm long:
Gleditsia triacanthos (honey locust)






8. Leaflets small and symmetric, fruit a relatively thin legume, non-native escaped species:
Albizia julibrissin (mimosa)

8. Leaflets large and asymmetric, fruit a large woody legume, not common in the wild, but often planted:
Gymnocladus dioicus (Kentucky coffeetree)





9. Lateral buds hidden under hollow petiole base, fruit a legume: go to 10

9. Lateral buds evident and axillary, fruit not a legume: go to 12






10. Leaflets small, about 3 cm long, elliptical, twigs may have visible spines or prickles: go to 11

10. Leaflets large, about 5 to 10 cm long, leaflets alternate on rachis and ovate, twigs without visible spines or prickles, bark light gray and smooth:
Cladrastis kentukea (yellow-wood)






11. Leaflet margin without teeth, node usually with a pair of spines, bark deeply furrowed, furrows often with orange tinge, legume small, about 5 cm:
Robinia pseudoacacia (black locust)

11. Leaflet margin with teeth, twigs usually with simple or branched thorns, legume about 30 cm long (leaves may be twice pinnate and once pinnate on the same tree):
Gleditsia triacanthos (honey locust)






12. Leaves with 5 or more pairs of lateral leaflets: go to 13

12. Leaves with mostly fewer than 4 pairs of lateral leaflets: go to key of hickories





13. Sap milky, fruit a red or brown berrylike fruit, a small tree or bush: go to key of sumacs

13. Sap not milky, fruit winged or a nut and not berrylike, may be a large tree: go to 14






14. Terminal leaflet present, fruit a samara, bark light gray and thin with distinctive pattern, leaflets with glands at base, leaves somewhat malodorous:
Ailanthus altissima (tree of heaven)

14. Terminal leaflet often absent, fruit a nut, bark dark with prominent V-shaped furrow, pith of small twigs chambered:
Juglans nigra (black walnut)






15. Leaflets 3-5, twigs green, fruit a double samara:
Acer negundo (box elder)

15. Leaflets 7-11, twigs not green, fruit a single samara: go to 16






16. Bark prominently diamond patterned, diamonds 3 to 5 cm long, twigs not angled or winged near tip:
Fraxinus americana  (white ash)

16. Bark divided into plate-like scales, twigs 4-angled to 4-winged most obviously near tips:
Fraxinus quadrangulata (blue ash)