Sotacaballo
Zygia longifolia
Native Region
Mexico to South America
Max Height
10-20 meters (33-65 feet)
Family
Fabaceae
Conservation
LC
Uses
Distribution in Costa Rica
Legend
Elevation
0-1200m
Regions
- Guanacaste
- Puntarenas
- Alajuela
- Limón
- San José
- Cartago
- Heredia
Season
Flowering
Mar-May
Fruiting
May-Jul
Sotacaballo (Riverside Mimosa)
The Sotacaballo (Zygia longifolia) is one of the most characteristic trees of Costa Rica's waterways. Its distinctive habit of leaning dramatically over rivers and streams provides essential shade for aquatic life while its roots stabilize banks against erosion. The powder-puff flowers are a favorite of bees and hummingbirds.
Quick Reference
- Scientific Name
- Zygia longifolia
- Family
- Fabaceae (Legume)
- Max Height
- 10-20 m (33-65 ft)
- Trunk Diameter
- Up to 60 cm
- Conservation
- Least Concern
- Key Feature
- Leaning riverbank habit
iNaturalist Observations
Community-powered species data
1200
Observations
186
Observers
📸 Photo Gallery
Photos sourced from iNaturalist community science database. View all observations →↗
Taxonomy and Classification
- Zygia: Greek for "yoke," referring to paired leaflets - longifolia: Latin for "long leaves" - Sotacaballo: Spanish, meaning "horse's tail" or "under the horse" (unclear origin) - Also known as Suribio, Guabillo
Common Names
| Language/Region | Common Name(s) | Meaning |
|---|---|---|
| English | Riverside Mimosa, Wild Tamarind | Descriptive names |
| Spanish (Costa Rica) | Sotacaballo, Suribio | Traditional names |
| Spanish (Panama) | Guabillo | Little Guaba |
| Spanish (Colombia) | Guamo de Río | River Guamo |
| Mayan | Several local names | Indigenous origins |
Physical Description
Overall Form
The Sotacaballo is a small to medium evergreen tree with a distinctive growth habit. It almost always leans toward water, often at dramatic angles, with its branches sweeping over the river surface. The trunk frequently forks low, creating multiple stems that arch gracefully over waterways.
Distinctive Features
Leaves
- Type: Bipinnately compound
- Leaflets: 2-4 pairs of pinnae
- Size: Each leaflet 4-12 cm long
- Shape: Oblong, asymmetrical
- Color: Dark glossy green
- Feature: Leaves fold at night
Bark
- Color: Grayish-brown
- Texture: Smooth to slightly rough
- Lenticels: Small, visible
- Feature: Sometimes with lichens
Flowers
- Type: Powder-puff mimosa
- Size: 3-5 cm diameter
- Color: White to cream
- Stamens: Numerous, showy
- Fragrance: Sweet, attracts bees
- Timing: Dry to early wet season
Fruits
- Type: Flattened pod
- Size: 8-15 cm long
- Color: Green to brown
- Shape: Often twisted/curved
- Seeds: 4-8 per pod
Ecological Importance
Riverine Ecosystem Services
Sotacaballo is fundamental to healthy river ecosystems in Costa Rica. Its shade cools water temperatures essential for fish and aquatic invertebrates, while fallen leaves provide food for aquatic food webs.
Stream Benefits
- Shade provision: Cools water 2-4°C
- Erosion control: Root networks stabilize banks
- Leaf litter: Base of aquatic food web
- Fish habitat: Roots provide refuge
- Insect habitat: Overhanging branches drop food
Terrestrial Benefits
- Nitrogen fixation: Enriches soil
- Pollinator support: Important bee plant
- Bird habitat: Nesting and foraging
- Corridor function: Connects forest fragments
Wildlife Relationships
| Animal Group | Use | Importance |
|---|---|---|
| Native bees | Nectar and pollen | Critical food source |
| Hummingbirds | Flower nectar | Regular visitors |
| Fish | Shade and insects | Thermal refuge |
| Monkeys | Travel corridors | Movement along rivers |
| Kingfishers | Hunting perches | Overhanging branches |
Distribution in Costa Rica
Sotacaballo is found throughout Costa Rica wherever there are rivers, streams, or permanent water sources from sea level to about 1,200 meters. It's one of the most commonly seen trees along waterways.
Key Observation Sites
| Location | Province | Setting | Access |
|---|---|---|---|
| Tortuguero canals | Limón | Lowland waterways | Boat tours |
| Río Tárcoles bridge | Puntarenas | Pacific river | Roadside viewing |
| Caño Negro | Alajuela | Wetland reserve | Boat tours |
| Most rivers nationwide | All provinces | Natural streams | Various |
| Urban streams | San José area | Riparian remnants | Walking paths |
Traditional Uses
Cultural and Practical Applications
Medicinal Uses
- Bark tea for digestive issues
- Leaf preparations for skin conditions
- Traditional fever remedy
- Anti-inflammatory applications
Practical Uses
- Living fence posts
- Firewood (moderate quality)
- Bank stabilization
- Shade for cattle watering areas
- Bee forage for honey production
Growing Information
Cultivation Requirements
| Factor | Requirement | Notes |
|---|---|---|
| Climate | Tropical, wet or seasonal | Needs water access |
| Temperature | 22-32°C (72-90°F) | No frost tolerance |
| Water | Riparian or high water table | Requires constant moisture |
| Soil | Alluvial, sandy to clay | Flood tolerant |
| Light | Full sun to partial shade | Best growth in full sun |
| Propagation | Seeds or cuttings | Seeds germinate easily |
Restoration Planting
Sotacaballo is excellent for:
- River bank restoration projects
- Aquatic habitat improvement
- Buffer zone establishment
- Erosion control plantings
- Agroforestry near water
Similar Species
| Species | Scientific Name | Key Differences |
|---|---|---|
| Guaba | Inga spp. | Different leaf structure, edible pulp |
| Cenízaro | Samanea saman | Much larger tree, different habitat |
| Guanacaste | Enterolobium cyclocarpum | Ear-shaped pods, savanna habitat |
| Other Zygia species | Zygia spp. | Similar but different leaflet details |
Interesting Facts
Cultural Significance
The Sotacaballo is deeply woven into the rural landscape of Costa Rica. Its presence along rivers has made it a natural landmark for generations—farmers often use these distinctive leaning trees as reference points when describing locations. The tree's consistent association with healthy waterways has made it a symbol of clean rivers and sustainable land use. In regions where rivers still run clear, the arching silhouettes of Sotacaballo trees remain a reassuring sign of ecological health.
Where to See Sotacaballo
Where to Find Sotacaballo in Costa Rica
Best Observation Sites:
- Tortuguero canals — Classic riverine habitat, boat tours
- Caño Negro Wildlife Refuge — Abundant along waterways
- Río Tárcoles — Visible from bridge and boat tours
- Sarapiquí River area — Common along riverbanks
- Río Pacuare — Rafting trips offer excellent views
Urban/Accessible:
- Central Valley streams — Remnant riparian habitat
- La Selva Biological Station — Research trails along rivers
- Tirimbina Reserve — Forest and river walks
For the best Sotacaballo experience, take a boat tour during dry season (December-April) when rivers are lower and the dramatic lean of these trees over the water is most pronounced. The flowering period (March-May) adds powder-puff blooms to the scene.
External Resources
Community observations and photos
Global distribution data
Botanical nomenclature and specimens
Kew Gardens taxonomic information
References
📚 Scientific References & Further Reading
Barneby, R.C. & Grimes, J.W. (1996). Silk Tree, Guanacaste, Monkey's Earring: A Generic System for the Synandrous Mimosaceae of the Americas. Memoirs of the New York Botanical Garden
Zamora, N. et al. (2004). Árboles de Costa Rica Vol. III. INBio, Santo Domingo de Heredia
Holdridge, L.R. & Poveda, L.J. (1975). Árboles de Costa Rica Vol. I. Centro Científico Tropical, San José
