Family: Fabaceae
Guilandina major (formerly Caesalpinia major) is a thorny, scrambling shrub or woody vine native from Madagascar across tropical Asia, the Pacific, and the Neotropics. In Hawaiʻi, it is either naturalized or possibly native and has been documented since at least 1864–1865. The plant occurs in gulches, on talus slopes, and along the edges of open, mesic coastal forests from near sea level up to about 1,500 feet in elevation. It is found on Niʻihau, Oʻahu, Molokaʻi, Lānaʻi, and Hawaiʻi Island. Guilandina major is recognizable by its arching, spiny stems, glossy compound leaves, yellow flowers, and large, spiny seed pods containing hard, rounded seeds. Historically, these durable seeds have been used for ornamentation and traditional crafts, and the plant’s dense, thorny growth has sometimes been used as a natural barrier.
Although Guilandina major has a long history in Hawaiʻi, it can spread aggressively under favorable conditions. Its thorny stems may form dense thickets that limit access and compete with surrounding vegetation, particularly in disturbed or coastal areas. The hard seeds are capable of dispersing by water, allowing the plant to spread along shorelines and drainage areas. While it is not currently considered a major invasive threat statewide, continued monitoring is important, especially in sensitive coastal and forest edge habitats where it could expand and affect native plant communities.
High Risk Traits:
- Naturalized outside native range (Norfolk Island, Hawaii)
- Highly suited to tropical/subtropical climates
- Congeneric weed known (Caesalpinia sepiaria)
- Spiny, climbing, thicket-forming
- Human-dispersed (jewelry, ornamental trade)
- Water-dispersed (coastal species)
- Dense thickets impede movement
Low Risk Traits:
- Non-toxic, non-parasitic, non-allelopathic
- Not shade-tolerant
- Not wind-dispersed
- Low seed production (large seeds)
- No vegetative reproduction
