Family: Fabaceae

Origin, Description & Uses
Leucaena leucocephala ‘Tarramba’ (Tarramba) is a fast-growing, nitrogen-fixing tree originally derived from Leucaena leucocephala, which is native to southern Mexico and Central America. The ‘Tarramba’ selection is an improved cultivar developed for vigorous growth, high biomass production, and adaptability to a range of tropical and subtropical environments. It typically forms a small to medium-sized tree with finely divided, feathery leaves and produces clusters of creamy-white, pom-pom-like flowers followed by abundant seed pods. This cultivar is widely promoted in agroforestry systems for livestock fodder, green manure, soil improvement, erosion control, shade, and fuelwood production due to its rapid growth and ability to enrich soils with nitrogen.

Risks & Threats
Although Leucaena leucocephala ‘Tarramba’ is currently not known to be naturalized in the Hawaiian Islands, it does possess traits that are cause for concern, and which could detrimentally impact tropical island ecosystems. Like other forms of leucaena, it can grow and spread aggressively, producing large quantities of long-lived seeds that may allow it to establish and form dense stands under favorable conditions. Its nitrogen-fixing ability can alter soil chemistry, potentially favoring its own spread and changing native plant communities. In addition, it may compete strongly with native vegetation for light, water, and space, and can contribute to increased fire risk by producing abundant woody biomass. Given these characteristics, caution is warranted, and planting should be carefully considered in favor of low-risk or native alternatives.

High Risk Traits:

• Broad climate suitability (tolerates cooler temps)
  
• Adapted to tropical/subtropical regions
  
• Allelopathic (inhibits other plants)
  
• Toxic to non-ruminant animals (mimosine)
  
• Host for psyllids and scale insects
  
• Tolerates wide range of soil types (incl. aluminum, mild acidity)
  
• Nitrogen-fixing (alters soil chemistry)
  
• Produces viable seed
  
• Self-compatible (no pollinator needed)
  
• Intentionally dispersed by people
  
• Wind-dispersed seeds
  
• Water-dispersed seeds
  
• Seeds survive animal gut passage
  
• Persistent seed bank (>1 year)
  
• Tolerates cutting, coppicing, and fire

Low Risk Traits:

• No spines, thorns, or burrs
  
• Palatable to grazing animals
  
• No evidence of human toxicity
  
• No vegetative spread
  
• No seed dispersal by birds or external animal attachment
  
• Seeds too large for produce contaminant
  
• No specialist pollinators required