To identify a tree with pinnately compound leaves, first confirm that you are looking at one leaf divided into leaflets—not several simple leaves growing along a twig. The leaflets should attach along a shared central stalk called the rachis, creating a feather-like form. Then narrow the possibilities using leaf arrangement, leaflet number and margins, buds, bark, fruit, flowers, odor, habitat, and geography.
To identify a tree with pinnately compound leaves, first confirm that you are looking at one leaf divided into leaflets—not several simple leaves growing along a twig. The leaflets should attach along a shared central stalk called the rachis, creating a feather-like form. Then narrow the possibilities using leaf arrangement, leaflet number and margins, buds, bark, fruit, flowers, odor, habitat, and geography.
As an Amazon Associate I earn from qualifying purchases.
What “pinnately compound” means
A compound leaf is a single leaf divided into separate leaflets. In a pinnately compound leaf, those leaflets are arranged along both sides of a central rachis, much like the barbs of a feather. The entire structure attaches to the twig through one main leaf stalk, or petiole.
A leaflet is not an independent leaf. One of the most useful field clues is the absence of an axillary bud at the base of each leaflet. Buds occur at the base of true leaves where they attach to a twig; leaflets attached to a rachis do not normally have their own buds.
#1 Best Overall
Three terms to distinguish
- Simple leaf: one continuous leaf blade, even if its veins branch in a feather-like pattern.
- Once-pinnately compound leaf: one row of leaflets attached along a rachis.
- Twice-pinnately compound, or bipinnate, leaf: the main rachis carries smaller side axes, called pinnae, and those axes carry the leaflets. Silk tree is a familiar example.
Do not confuse pinnate venation with pinnate compoundness. A simple oak or beech leaf can have a central midrib with side veins arranged like a feather, but its blade is not divided into separate leaflets.
A reliable field-identification sequence
- Confirm the leaf architecture. Look for one petiole, a continuous rachis, and leaflets arranged along the rachis. Decide whether the leaf is once-pinnate or twice-pinnate.
- Check how leaves are arranged on the twig. Leaves may be opposite—paired at the same node—or alternate, with one leaf per node. This is often more useful than leaflet shape.
- Count the leaflets. Record an approximate number, whether there is a terminal leaflet, and whether the leaflet pairs are regular or irregular.
- Inspect leaflet details. Note margins, shape, size, tip, base, texture, hairiness, and whether the leaflet stalks are opposite or staggered.
- Examine the rachis. It may be winged, grooved, swollen, or unusually persistent after the leaflets fall.
- Inspect twigs and buds. Look for opposite or alternate branching, a terminal bud, spines, distinctive leaf scars, and unusual pith.
- Use fruit, flowers, bark, odor, and habitat as confirmation. These features often separate species that have similar leaves.
- Account for season and region. A winter specimen may require bud, bark, twig, fruit, and leaf-scar characters. A species common in the eastern United States may not be a reasonable identification elsewhere.
First distinction: opposite or alternate leaves?
Stand back from the individual leaf and examine the twig. If two leaves emerge directly opposite each other at each node, the tree is opposite-branched. If the leaves alternate from side to side along the twig, it is alternate-branched.
Among North American trees with pinnately compound leaves, opposite branching strongly suggests ash or boxelder, although other plants can complicate the picture. Alternate branching is typical of walnut, hickory, black locust, tree-of-heaven, and many sumacs.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →| Initial observation | Possibilities to investigate |
|---|---|
| Opposite leaves and usually 5–11 leaflets | Ash |
| Opposite leaves and usually 3–7 leaflets, with paired samaras | Boxelder |
| Alternate leaves with many toothed leaflets and a round nut | Black walnut |
| Alternate leaves with husked nuts and variable leaflet hairiness | Hickory or butternut |
| Alternate leaves, mostly smooth-edged leaflets, and possible paired spines | Black locust |
| Very long leaves with many mostly smooth-edged leaflets and basal glands | Tree-of-heaven |
| Compound leaves, often colony-forming, with dense red fruit clusters | Sumac |
This table provides starting points, not final identifications. Several of these groups overlap in leaflet number and shape.
Leaflet count and terminal leaflets
Count the leaflets on a mature, undamaged leaf when possible. Also determine whether the leaf ends in a single leaflet or in a pair.
- Odd-pinnate: a single terminal leaflet ends the rachis.
- Even-pinnate: the rachis ends in a pair of leaflets. Some plants instead have a tendril, spine, or modified structure at the tip.
This distinction is useful, especially among legumes, but it should not be used alone. A damaged leaf may have lost its terminal leaflet, and some species vary in leaflet number or arrangement.
Common trees with pinnately compound leaves
Ash (Fraxinus)
True ashes usually have opposite branching and compound leaves with approximately five to eleven leaflets. Leaflet margins may be smooth or toothed, depending on the species. The fruit is an unpaired, winged samara, often described as a key ash feature.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Boxelder is a frequent look-alike because it also has opposite leaves and compound foliage. “Mountain ash,” however, is not a true ash: it generally refers to Sorbus, a different genus. Do not identify a tree as Fraxinus solely because its common name contains “ash.”
Rank #2
- Pocket Guide to Trees and Shrubs of North America
- Pocket Guide to Trees and Shrubs of North America
- National Geographic Maps
Boxelder (Acer negundo)
Boxelder is unusual among North American maples because its leaves are compound. The leaves are opposite and commonly have three to seven leaflets, often fewer than an ash. Its paired samaras—the familiar two-winged maple fruits—are a strong confirmation clue.
An opposite-branched tree with compound leaves and paired samaras points toward boxelder or another maple lineage. Ashes produce unpaired samaras, so fruit attachment is more informative than a general resemblance between the leaves.
Black walnut (Juglans nigra)
Black walnut has alternate, usually odd-pinnate leaves with approximately 13–23 toothed leaflets. The leaves are generally shorter than the very long leaves of tree-of-heaven. Its fruit is a round nut enclosed in a greenish or brown husk, not a winged samara.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteWhen leaves are absent, inspect the twig. Black walnut has a terminal bud and chambered pith. Those twig characters can be valuable when a fallen leaf has been damaged or when identification is needed in winter.
Butternut (Juglans cinerea)
Butternut is another alternate-leaved walnut with pinnately compound foliage. Its elongated, ridged nuts and overall twig and bark characteristics help distinguish it from black walnut and other compound-leaved trees. Because walnut species can vary by age and growing conditions, use the fruit and twig together with the leaf.
Hickories (Carya)
Hickories have alternate, pinnately compound leaves and nuts enclosed in husks. Species-level identification depends on a combination of leaflet number, leaflet size, underside hairiness, buds, bark, and nut features.
Mockernut hickory, for example, may have fuzzy leaflet undersides and a citrus-like odor when crushed. Odor is supporting evidence rather than a stand-alone test: the strength of an odor can vary, and crushing unknown plant material is not advisable if you cannot safely handle it.
Free tools Windows power users keep installed
One-click scans. No signup required.
Black locust (Robinia pseudoacacia)
Black locust has alternate, once-pinnately compound leaves, commonly with seven to nineteen elliptical or ovate leaflets. The leaflet margins are generally entire, or smooth rather than toothed.
Look for the following combination:
- paired spines at some leaf bases;
- no obvious terminal bud;
- lateral buds partly hidden beneath the bark near the leaf scar;
- fragrant white, pea-like flowers; and
- flat brown pods later in the season.
A field description combining those traits would be much stronger than “a tree with oval leaflets.” For example: alternate, once-pinnately compound leaves with 7–19 smooth-edged leaflets, paired spines at some leaf bases, no terminal bud, white pea-like flowers, and flat brown pods is consistent with black locust. That is a diagnostic comparison, not a determination about an unseen specimen.
Honey locust (Gleditsia triacanthos)
Honey locust may have either once-pinnate or twice-pinnate leaves. Wild forms can have conspicuous branched thorns on the trunk and branches. Its long pods and regular flowers help separate it from black locust.
When the foliage is twice divided into small pinnae, do not describe it simply as an ordinary pinnate leaf. The two levels of branching are a significant identification feature.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Sumacs (Rhus and related taxa)
Sumacs commonly have pinnately compound leaves and may form dense colonies or thickets. Staghorn sumac is a notable look-alike for tree-of-heaven. Dense clonal growth and conspicuous red fruit clusters can help distinguish it.
In sumac identification, the growth habit and fruit cluster are often more useful than the shared feather-like leaf shape. Take care around unfamiliar plants and do not assume every red-fruited sumac is interchangeable with another species.
Tree-of-heaven (Ailanthus altissima)
Tree-of-heaven has unusually long pinnately compound leaves, commonly about one to four feet long, with roughly 10–40 leaflets. The leaflet margins are generally smooth, and each leaflet commonly has one or two glandular teeth near its base. Crushed foliage may have a strong, unpleasant odor.
Tree-of-heaven is invasive in much of the United States, but that does not make every long compound leaf a tree-of-heaven. Black walnut, sumac, hickory, ash, locust, and boxelder can all be confused with it at a glance. Confirm the diagnosis with leaflet bases, twig characters, fruit, branching habit, and regional context before deciding whether control work is appropriate.
Recommended Free Tools
Important look-alikes and mistakes
Pinnate veins versus pinnate leaves
A leaf with one midrib and side veins is not necessarily compound. If the blade is continuous from base to tip, it is a simple leaf with pinnate venation.
Virginia creeper
Virginia creeper is palmately compound, not pinnately compound. Its five leaflets radiate from a single point at the end of the petiole rather than lining both sides of a rachis.
Poison hemlock
Poison hemlock is not a tree. Its leaves may be doubly or triply pinnately compound, and the plant is highly poisonous. Avoid handling or ingesting unknown foliage. If a plant could be poison hemlock, rely on a qualified local identification resource rather than crushing it for an odor test.
Common names
Common names are convenient but unreliable. Mountain ash is not a true ash, and names can vary by region. Use the scientific name only when the physical evidence and a geographically appropriate key support it.
How to identify a leafless tree in winter
Without leaves, shift the investigation to the twig and surrounding tree:
- Determine whether twigs and branches are opposite or alternate.
- Look for a terminal bud and note its size, shape, color, and hairiness.
- Inspect leaf scars for their shape and vascular-bundle marks.
- Check for spines, persistent rachis segments, and distinctive buds.
- Cutting a twig should be reserved for appropriate specimens and safe, permitted situations; chambered or spongy pith can be informative in some trees.
- Look for persistent pods, nuts, samaras, or red fruit clusters.
- Use bark and growth habit only as supporting evidence, not as the sole basis for a difficult identification.
Black walnut illustrates why winter characters matter: its terminal bud and chambered pith can support an identification when the large compound leaves are gone.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to record a defensible identification
For a construction, landscaping, or property-maintenance record, describe the evidence rather than recording only a guess. Include:
- once-pinnate or twice-pinnate structure;
- opposite or alternate leaves;
- approximate leaflet count;
- odd- or even-pinnate termination;
- leaflet margins and notable basal features;
- rachis characteristics;
- buds, spines, and leaf scars;
- bark, fruit, flowers, or odor; and
- location, habitat, season, and whether the tree is cultivated, naturalized, or growing in a colony.
A useful note might read: “Alternate, once-pinnately compound leaves with 7–19 smooth-edged leaflets; paired spines present at several leaf bases; no terminal bud observed; white pea-like flowers and flat brown pods present. Features are consistent with black locust.”
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallUse cautious wording such as consistent with when the specimen has only leaves or a single photograph. Juvenile foliage, seasonal variation, hybridization, environmental stress, missing terminal leaflets, and regional differences can all make a one-character identification unreliable.
Best Value
Choosing a field guide
A tree identification field guide is useful because difficult compound-leaved trees are rarely separated by one photograph or one leaflet count. Choose a guide that shows leaves, twigs, bark, fruit, flowers, range, and similar species—not leaves alone.
- Arbor Day Foundation’s What Tree Is That?: a 164-page, water-resistant guide using a step-by-step approach and covering 250 common North American trees.
- National Audubon’s Trees of North America: a broader reference covering more than 540 species, with photographs of leaves, bark, fruit, flowers, seasonal color, range maps, and similar species.
- Macmillan’s Trees of North America: A Guide to Field Identification: organized around tree shape, bark, leaves, flowers, fruit, and twigs.
Check that the edition and geographic coverage match the area where the tree grows. A regional guide is often more useful for exact identification than a very broad guide with limited local detail.
Safety and property-work considerations
Correct identification matters before pruning, removal, herbicide application, or habitat work. Tree-of-heaven, for example, should not be confused with native walnut or sumac before control measures are planned. Likewise, unknown foliage should not be tasted or crushed casually, particularly when poison hemlock is possible.
For a tree near a structure, utility line, roadway, or active work zone, identification is only one part of the decision. Follow site safety procedures, check local permissions and regulations, and have a qualified arborist assess hazards such as dead limbs, cavities, decay, lean, and root damage.
Frequently Asked Questions
How can I tell whether a leaf is pinnately compound?
A pinnately compound leaf has multiple leaflets arranged along both sides of a shared central rachis. The entire structure attaches to the twig through one petiole, and the leaflets do not have individual axillary buds. A simple leaf may have pinnate veins, but its blade remains continuous.
Which trees with pinnately compound leaves have opposite branching?
Opposite leaves strongly suggest ash or boxelder among common North American trees with compound foliage. Ash commonly has five to eleven leaflets, while boxelder often has three to seven and produces paired maple samaras. Confirm with buds, twigs, and fruit.
How do I distinguish black walnut from tree-of-heaven?
Black walnut usually has alternate leaves with about 13–23 toothed leaflets and round husked nuts. Tree-of-heaven usually has much longer leaves, roughly 10–40 mostly smooth-edged leaflets, and glandular teeth near the leaflet bases. Twig features and fruit provide additional confirmation.
Is Virginia creeper pinnately compound?
Virginia creeper is palmately compound: its five leaflets radiate from one point. Pinnately compound leaves have leaflets arranged along both sides of a central rachis.
Is poison hemlock a tree with pinnately compound leaves?
No. Poison hemlock is a poisonous herbaceous plant, not a tree. Its leaves can be doubly or triply pinnately compound. Avoid handling or ingesting unknown foliage and seek qualified local identification if it is a possibility.
Can I identify a pinnately compound-leaved tree without leaves?
Yes. Compound-leaved trees can be identified in winter by opposite or alternate twigs, terminal buds, leaf scars, pith, spines, bark, persistent fruit, and growth habit. Black walnut, for example, has a terminal bud and chambered pith.
The Bottom Line
The most reliable identification combines several clues: confirm the feather-like compound structure, determine opposite or alternate branching, count and inspect the leaflets, then verify the result with buds, bark, fruit, flowers, twig features, habitat, and region. A single fallen leaf is rarely enough for a confident species-level diagnosis.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsQuick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
