Guarumo

Cecropia obtusifolia is native to the tropical Americas, ranging from southern Mexico through Central America to Colombia, Ecuador, and Venezuela.

• Found from sea level to approximately 1,500 meters elevation
• Thrives in tropical moist and wet forests, as well as disturbed areas
• The genus Cecropia comprises over 100 species, making it one of the largest genera of Neotropical trees
• Center of diversity is in the Amazon Basin and the Andean foothills

Guarumo is a medium-sized, fast-growing deciduous tree typically reaching 10 to 25 meters in height, with a trunk diameter of 20 to 40 cm.

Trunk & Bark:
• Trunk is straight, slender, and often slightly swollen at the base
• Bark is smooth to slightly rough, grayish to pale brown
• Internodes are hollow, providing nesting habitat for Azteca ants

Leaves:
• Large, palmate leaves with 8 to 12 lobes, resembling a hand
• Leaf blades measure 20 to 50 cm in diameter
• Upper surface is dark green; lower surface is densely covered with fine white hairs (tomentose)
• Petioles are long (15–30 cm) and pithy

Flowers & Fruit:
• Dioecious — male and female flowers occur on separate trees
• Flowers are small, inconspicuous, arranged in spike-like inflorescences
• Female infloences produce long, pendulous spikes of tiny fruits
• Fruits are small, fleshy achenes (~2 mm long), produced in large quantities
• Fruiting spikes can reach 10 to 20 cm in length
• Fruits ripen to a brownish color and are dispersed primarily by birds and bats

Guarumo is a classic pioneer species, among the first trees to colonize forest gaps, landslides, roadsides, and other disturbed areas.

Habitat:
• Prefers full sun and is rarely found in the shaded understory of mature forests
• Commonly found along riverbanks, forest edges, and secondary growth
• Tolerant of poor, degraded soils

Symbiosis with Azteca Ants:
• One of the most well-known examples of plant-ant mutualism in the tropics
• Hollow stems (domatia) provide nesting chambers for colonies of Azteca ants
• Ants feed on glycogen-rich Müllerian bodies produced at the base of leaf petioles
• In return, ants aggressively defend the tree against herbivores, vines, and competing vegetation
• This mutualism is so effective that Guarumo trees with ant colonies suffer significantly less herbivory

Seed Dispersal:
• Fruits are consumed by over 50 species of birds, including toucans, tanagers, and cotingas
• Bats also contribute to seed dispersal
• Seeds germinate rapidly in full sunlight, often within days of landing on exposed soil
• A single tree can produce thousands of fruits per season

Guarumo is occasionally cultivated for reforestation and ecological restoration projects due to its rapid growth and ability to stabilize degraded soils.

Light:
• Requires full sun; does not tolerate shade
• Ideal for open, exposed sites

Soil:
• Adaptable to a wide range of soil types, including poor, compacted, or degraded soils
• Prefers well-drained conditions but tolerates periodic flooding

Watering:
• Moderate water requirements once established
• Young trees benefit from regular watering during dry periods

Temperature:
• Thrives in tropical climates with temperatures between 20°C and 30°C
• Not frost-tolerant

Propagation:
• Primarily by seed — seeds germinate readily in moist, sunny conditions
• Can also be propagated from cuttings
• Growth rate is exceptionally fast; trees can reach 5 meters in the first year under optimal conditions