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LanternflyWatch

Visual Field Guide · Host Plant ID

Identify
Tree of Heaven

Ailanthus altissima is SLF's #1 food source. Every one near you supports 3–5x more lanternflies than areas without it. Learn to spot it — then report it.

Report ToH Near You →Read Full Removal Guide →
3–5x
Higher nymph counts on properties with ToH
70+
Host plants SLF can use — ToH is #1 preferred
1–4 ft
Compound leaf length — largest in eastern US
10 ft/yr
Growth rate from root sprouts after cutting
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Fastest ID Method

The Smell Test: Crush a Leaf

Tree of Heaven leaves, when crushed, smell like peanut butter gone wrong — a distinctive rancid, burnt peanut or cat urine smell caused by ailanthone and related compounds. No native look-alike smells like this.

Crush a single leaflet between your fingers. If it smells foul — it's ToH.

Native sumac smells mildly astringent. Black walnut smells strongly of walnut husks. Neither smells like ToH. Male ToH trees tend to release the rancid odor even more strongly than females.

Visual Field Guide

5 Key ID Features

Use these in combination. The gland teeth + smell test together are essentially definitive.

🌿Feature 1 of 5

Compound Leaves

10–41 leaflets arranged in pairs along a central stem (pinnately compound). Each leaflet is 2–6" long, lance-shaped with smooth edges — except at the base. The entire compound leaf can reach 1–4 FEET long.

  • Leaflets are alternate on the main stem
  • Leaf size alone is the first hint — no native tree has leaves this large
  • Leaves emerge late (May) and drop early (October)
  • Underside of leaflets is pale, slightly lighter than the top surface

Field Tip

Hold the compound leaf at arm's length. If it's longer than your arm from elbow to fingertip, you're likely looking at ToH.

vs. Look-alikes

Sumac has similar compound leaves but leaflets have toothed edges all the way around, and stems are hairy. Walnut has similar leaves but leaflets are hairy underneath and smell nutty when crushed.

🔍Feature 2 of 5

Gland-tipped Teeth (Definitive Feature)

This is the #1 most reliable ID feature. At the base of EACH leaflet, look for 1–3 small "teeth" — tiny lobes or bumps — each with a dark gland dot at the tip. No native compound-leafed tree in the eastern US has this exact combination.

  • Flip a leaflet over and look at the very base (near where it attaches to the stem)
  • You will see 1–3 tiny bumps, each tipped with a tiny dark dot (the gland)
  • The glands secrete a substance that contributes to the foul odor
  • These are present year-round — even on dried herbarium specimens
  • The rest of the leaflet edge is completely smooth — teeth ONLY at the base

Field Tip

Run your fingernail along the base of a leaflet. You can FEEL the gland teeth as tiny bumps before you even see them. Each bump has a darker tip when examined closely.

🌲Feature 3 of 5

Bark and Stems

Young stems are smooth and gray-green, covered in pale lenticels (small raised dots like freckles). Older bark is light gray with shallow, irregular interlacing furrows — often described as resembling the skin of a cantaloupe.

  • Young stems: smooth, gray-green, with scattered pale raised lenticels
  • Mature bark: light gray, cantaloupe-pattern furrows — NOT deeply ridged like oak
  • Stems are thick and pithy inside — tan spongy pith when cut
  • After leaves fall, look for large shield-shaped leaf scars — often described as a "monkey face"
  • New growth is extremely fast: 6–10 feet per year from a stump or root sprout

Field Tip

Slice a small branch crosswise with a pocket knife. ToH pith is soft, tan, and spongy — more like a straw than solid wood. Native trees have harder, denser pith.

🍂Feature 4 of 5

Seeds (Samaras)

Female trees produce massive hanging clusters of papery, twisted seed pods (samaras) — each about 1.5" long, with the seed in the center of the wing. Clusters can contain hundreds of seeds and persist into winter.

  • Green when forming (summer), turning tan/rusty-brown in fall
  • Each samara is twisted like a propeller with the seed in the middle
  • Clusters can be enormous — a large female may produce thousands of seeds
  • Persist on the tree through winter, making winter ID straightforward
  • Only female trees produce seeds — male trees smell worse (release more odor)

Field Tip

In fall and winter, look for large hanging clusters of papery twisted wings. No native tree in the eastern US produces seed clusters this size in this shape. If you see a tree plastered with tan papery spirals in December — it's ToH.

📍Feature 5 of 5

Location Patterns

Tree of heaven is almost always a "weed tree" growing in disturbed ground. It thrives where native trees cannot — in compacted soil, alongside pavement, in urban gaps — and forms dense thickets from root sprouts.

  • Alleys, roadsides, railway corridors, vacant lots, forest edges — never in undisturbed forest
  • One parent tree sends up dozens of root sprouts, forming a thicket
  • In cities: look in building gaps, fence lines, median strips, cracked sidewalks
  • Can be 6" diameter in just 5 years — unusually fast for a hardwood
  • Produces allelopathic chemicals (ailanthone) that suppress competing plants around it

Field Tip

If you're in an alley or along a fence line and see a fast-growing tree with large compound leaves — assume ToH until proven otherwise. It is by far the most common large weed tree in mid-Atlantic urban corridors.

Common Mistakes

Look-alike Comparison

Five native trees commonly confused with Tree of Heaven. Know these before you pull out a saw.

TreeSimilar FeatureKey Difference
Staghorn SumacCompound leaves, same disturbed-ground habitatHairy stems and leaf undersides; leaflet teeth run the whole edge (not just base); red cone-shaped berry clusters; no foul odor
Black WalnutLarge compound leaves, fast-growingLeaflet teeth run the whole edge; smells strongly of walnut (not foul); has distinctive round green/black husked nuts; leaflets hairy underneath
Ash (Green or White)Compound leaves on large treesAsh leaflets are OPPOSITE each other on the stem; ToH leaflets are alternate. Ash bark is deeply diamond-furrowed. No gland teeth.
ElderberryCompound leaves, fast-growing in disturbed groundElderberry leaflets are much smaller (2–4"); stems have corky texture; distinctive small white flower clusters and dark berries; shrub-sized, not tree-sized
Mimosa (Silk Tree)Large compound-looking leaves in urban areasMimosa has DOUBLY compound leaves (leaflets on sub-branches, like a fern frond); pink fluffy flowers in summer; no foul odor; leaflets are tiny

Take Action

Found a Tree of Heaven?

Three actions, ordered by impact.

📍

1. Report It

Add it to the community ToH map so researchers can prioritize removal in your area. Takes 60 seconds.

Open ToH map →
🪓

2. Remove It

DIY removal guide with seasonal timing — cut-stump, foliar spray, and trap-tree strategies that actually work. Warning: cutting alone makes it worse.

Read removal guide →
📢

3. Tell Your Neighbors

Copy and share this message:

"Hey! There's a Tree of Heaven (invasive weed tree) growing nearby — it's the #1 food source for spotted lanternfly and can increase lanternfly counts 3–5x. Check out lanternflywatch.com/guides/toh-id to learn how to spot it, and report any you find at lanternflywatch.com/map/toh."

Related Guides

🦟

SLF Biology

All 4 life stages identified.

🔎

Is This an SLF?

Interactive ID checklist.

🗺️

ToH Map

Community ToH reporting.

🪓

Removal Guide

Cut-stump, spray & trap-tree methods.

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