Guarumo
Cecropia obtusifolia
Native Region
Tropical Americas
Max Height
15-25 meters
Family
Urticaceae
Conservation
LC
Uses
Distribution in Costa Rica
Legend
Elevation
0-1500m
Regions
- Limón
- Alajuela
- Heredia
- San José
- Puntarenas
- Cartago
Season
Flowering
Year-round
Fruiting
Year-round
Guarumo (Trumpet Tree)
The Guarumo (Cecropia obtusifolia), also called Trumpet Tree or Cecropia, is the quintessential pioneer tree of Neotropical forests. When a forest is cleared, a landslide occurs, or a large tree falls, Guarumo is among the first trees to colonize the opening. Its giant palmate leaves, hollow stems housing ant armies, and silver-white leaf undersides make it instantly recognizable. Where you see Guarumo, you see a forest healing itself.
Quick Reference
- Scientific Name
- Cecropia obtusifolia
- Family
- Urticaceae (Nettle Family)
- Max Height
- 15-25 m
- Trunk Diameter
- Up to 50 cm
- Conservation
- Least Concern
- Key Feature
- Palmate leaves, ant mutualism
iNaturalist Observations
Community-powered species data
4500
Observations
186
Observers
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Taxonomy and Classification
- Cecropia: Named after Cecrops, mythical first king of Athens - obtusifolia: Latin for "blunt-leaved" - Guarumo: From indigenous Caribbean languages - Trumpet Tree: Hollow stems were used as trumpets - Yarumo: Colombian name
Common Names
| Language/Region | Common Name(s) | Meaning |
|---|---|---|
| Spanish (Costa Rica) | Guarumo | Indigenous origin |
| Spanish (Colombia) | Yarumo | Indigenous origin |
| English | Trumpet Tree, Cecropia | Hollow stems / genus name |
| English (Belize) | Trumpet, Snakewood | Hollow stems / appearance |
| Portuguese | Embaúba | Tupi name |
Cecropia Species in Costa Rica
Costa Rica has several Cecropia species:
| Species | Distribution | Notes |
|---|---|---|
| C. obtusifolia | Lowland wet forests | Most common, smaller leaves |
| C. peltata | Caribbean lowlands | Larger, deeply lobed leaves |
| C. insignis | Mid-elevation forests | Often without ants |
| C. angustifolia | Higher elevations | Narrower leaf lobes |
Physical Description
General Form
The Guarumo is a fast-growing, short-lived tree with a distinctive open crown of large palmate leaves. The trunk is typically unbranched or sparingly branched, straight, and pale gray with prominent leaf scars. The hollow internodes are often home to fierce ant colonies. Everything about this tree is designed for rapid growth and quick colonization.
Distinctive Features
The Famous Leaves
- Type: Palmate (like a hand)
- Lobes: 7-11 deep lobes
- Size: 30-50 cm diameter
- Petiole: Very long (30-50 cm)
- Upper Surface: Dark green
- Lower Surface: Silvery-white (diagnostic!)
- Effect: Flash white when wind blows
Trunk and Stems
- Color: Pale gray to whitish
- Texture: Smooth with ring scars
- Structure: Hollow internodes
- Inhabitants: Azteca ants (usually)
- Branching: Sparse, often unbranched
Flowers and Fruit
- Type: Dioecious (separate male/female trees)
- Male Flowers: Catkin-like spikes
- Female Flowers: Finger-like clusters
- Fruit: Elongated, fleshy, many-seeded
- Color: Green to brownish when ripe
- Size: 5-10 cm long clusters
Roots and Growth
- Roots: Shallow, spreading
- Growth Rate: Extremely fast (2-3 m/year!)
- Light Need: Full sun required
- Strategy: Pioneer colonizer
- Lifespan: Short (20-40 years)
Guarumo trees are easy to spot even from far away: - Canopy Shape: Umbrella-like, open crown - Leaf Flash: Silvery undersides flash in wind - Position: Often at forest edges, roadsides - Companions: Look for sloths hanging in branches! On cloudy or windy days, the "flashing" of the silver leaf undersides makes Guarumo trees visible from kilometers away.
The Ant Mutualism
Azteca Ants: Live-In Bodyguards
An Ancient Partnership
The Guarumo-Azteca ant mutualism is one of the most famous plant-animal partnerships in tropical ecology: What the Tree Provides: - Housing: Hollow stems with pre-formed entrances - Food: Glycogen-rich "Müllerian bodies" at leaf bases - Security: Protected cavities for ant brood What the Ants Provide: - Defense: Fierce attacks on herbivores, vines, epiphytes - Pruning: Remove competing vegetation - Fertilizer: Ant waste nourishes the tree This partnership has evolved over millions of years and benefits both species enormously.
The Azteca Ant Defense
If you grab a Guarumo trunk without checking first: 1. Instant Alert: Vibrations alert ant colony 2. Mass Response: Hundreds of ants pour from holes 3. Painful Bites: Azteca ants bite aggressively 4. Chemical Weapons: Some spray formic acid The ants are especially active during the day. They attack anything that touches the tree—herbivorous insects, climbing vines, even people! Pro Tip: Before touching any Cecropia, look for the small holes near branch bases and petioles where ants enter and exit.
Myrmecophyte Adaptations
| Feature | Purpose | How It Works |
|---|---|---|
| Prostomata | Ant entrances | Pre-formed thin spots for ants to chew through |
| Müllerian Bodies | Ant food | Protein-rich growths at leaf bases |
| Hollow Stems | Ant housing | Chambered internodes for colonies |
| Trichilia | Food chambers | Special structures producing ant food |
Distribution and Habitat
Native Range
Geographic Distribution
Distribution in Costa Rica
Found throughout lowland and mid-elevation areas:
| Province | Abundance | Notes |
|---|---|---|
| Limón | Very Common | Caribbean lowlands, ideal habitat |
| Puntarenas | Very Common | Pacific wet forests, Osa |
| Alajuela | Common | Northern plains, foothills |
| Heredia | Common | Caribbean slope |
| San José | Occasional | Valley edges, disturbed areas |
| Guanacaste | Occasional | Wetter areas only |
Habitat Preferences
- Elevation: Sea level to 1,500 m
- Climate: Tropical wet to moist
- Rainfall: 2,000-5,000 mm/year
- Temperature: 22-32°C
- Soil: Tolerates poor soils
- Light: REQUIRES full sun
- Habitat: Forest edges, gaps, disturbed areas
Ecological Importance
The Pioneer's Role
Guarumo plays a critical role in tropical forest dynamics: Colonization: - First tree to establish in clearings - Seeds germinate in full sun - Grows 2-3 meters per year! - Creates shade for later successional trees Facilitation: - Shades out grasses and ferns - Improves soil conditions - Attracts seed dispersers - Creates perches for birds Transition: - Lives 20-40 years - Eventually shaded out by taller trees - Death creates light gaps for new growth Guarumo is the "nurse tree" that makes forest recovery possible.
Wildlife Relationships
The Sloth Connection
- Two-Toed Sloths: Primary food source
- Three-Toed Sloths: Major food tree
- Why: Leaves nutritious, easy to digest
- Behavior: Sloths sleep in Guarumo crowns
- Saying: "Find a Cecropia, find a sloth"
Bird Interactions
- Toucans: Eat ripe fruits
- Tanagers: Major fruit consumers
- Parrots: Eat fruits and seeds
- Seed Rain: Birds perch and "deliver" seeds
Mammal Visitors
- Bats: Major seed dispersers
- Monkeys: Eat fruits, disperse seeds
- Coatis: Climb for fruit
- Kinkajous: Nocturnal fruit eating
Insect Community
- Azteca Ants: Mutualist partners
- Caterpillars: Some specialists
- Flies: Visit flowers
- Beetles: Various associations
The Sloth's Best Friend
Three-toed sloths have a special relationship with Guarumo: - Diet: Cecropia leaves are preferred food - Digestion: Sloths' slow metabolism handles the leaves - Rest: Open crown is perfect for sunning - Camouflage: Gray fur blends with branches - Range: Sloths follow Cecropia distribution If you want to see sloths in Costa Rica, look for Guarumo trees first!
Human Uses
Traditional Uses
Medicine
- Leaves: Diabetes treatment (traditional)
- Bark: Respiratory conditions
- Sap: Wound healing
- Roots: Various preparations
- Modern Research: Antioxidant compounds
Materials
- Hollow Stems: Trumpets, flutes, blowguns
- Wood: Soft, light, matches, paper pulp
- Fiber: Rope and cordage
- Flotation: Rafts and floats
Conservation and Restoration
| Application | Use | Benefits |
|---|---|---|
| Reforestation | Pioneer planting | Fast growth starts succession |
| Erosion Control | Slope stabilization | Quick coverage |
| Wildlife Corridors | Stepping stones | Attracts seed dispersers |
| Research | Indicator species | Shows forest health |
| Education | Easy to observe | Visible ant mutualism |
Identification Guide
How to Identify Guarumo
Definitive Features:
- Large palmate leaves (like a hand with 7-11 fingers)
- Silvery-white leaf undersides
- Hollow stems with ant colonies
- Pale gray trunk with ring-shaped leaf scars
- Open, umbrella-like crown
- Forest edge or gap habitat
Where to See Guarumo in Costa Rica
| Location | Access | Notes |
|---|---|---|
| La Selva Biological Station | Research trails | Excellent examples with ants |
| Tortuguero National Park | Boat/trails | Common along waterways |
| Manuel Antonio NP | Trails | Look for sloths! |
| Caribbean Highway | Roadside | Everywhere along route |
| Arenal area | Roadsides | Regenerating forest |
| Any forest edge | Widespread | The most common pioneer tree |
To find sloths in Guarumo trees: - Time: Dawn or late afternoon (active periods) - Weather: After rain, sloths may be visible - Shape: Look for gray "lumps" in the crown - Movement: Watch for slow motion in leaves
- Guides: Local guides know the individual trees The open crown of Guarumo makes sloths more visible than in dense canopy trees!
External Resources
Community observations and photos
Sloth research and conservation
La Selva research station
References
📚 Scientific References & Further Reading
Janzen, D.H. (1969). Allelopathy by myrmecophytes: The ant Azteca as an allelopathic agent of Cecropia. Ecology 50: 147-153
Longino, J.T. (1991). Azteca ants in Cecropia trees: Taxonomy, colony structure, and behaviour. Ecological Monographs 61(1): 1-33
Montgomery, G.G. (ed.) (1985). The Evolution and Ecology of Armadillos, Sloths, and Vermilinguas. Smithsonian Institution Press
Where others see disturbance, the Guarumo sees opportunity. This remarkable tree is the living embodiment of ecological resilience—first to arrive when disaster strikes, first to offer shade and food, first to begin the long process of forest healing. Its partnership with fierce Azteca ants shows that cooperation can be fierce, and its role as sloth cafeteria reminds us that even "weedy" trees can be ecological keystones. Next time you see a Guarumo at a forest edge, don't see a common pioneer—see hope in action, the beginning of a forest's return.
