Family: Asteraceae
Origin, Description & Uses
Tridax procumbens (coat buttons, tridax daisy) is a low-growing, sprawling perennial herb native to Mexico and tropical America. It produces slender creeping stems that readily root where they touch the ground, along with small, daisy-like flower heads featuring white ray florets surrounding yellow centers. Because of its long flowering season and ability to thrive in poor, dry soils, it has occasionally been grown as a groundcover or valued for its role in attracting pollinators. In Hawaiʻi, it was first collected on Maui in 1922 and is now naturalized and relatively common in low-elevation, dry, disturbed habitats on Midway Atoll and all of the main Hawaiian Islands except Niʻihau.
Risks & Threats
Tridax procumbens is naturalized in Hawaiʻi and possesses traits that are cause for concern, including rapid growth, prolific seed production, and the ability to spread readily in disturbed areas. These characteristics allow it to form persistent populations that can compete with native vegetation and other desirable plants, contributing to the degradation of tropical island ecosystems. Because this species is already widespread in parts of Hawaiʻi, efforts should focus on managing existing populations and preventing its use or spread into areas where it is not yet widely established. Whenever possible, choose a low-risk or native alternative for landscaping or groundcover to help reduce the risk of further ecological impacts.
High Risk Traits:
- Broad climate suitability, and elevation range exceeds 1000 m, demonstrating environmental versatility
- Thrives in tropical climates
- Widely naturalized in Hawaiian Islands and worldwide in regions with tropical and subtropical climates
- Disturbance-adapted weed of numerous agricultural crops
- Allelopathic
- Host of several important crop pathogens
- Tolerates many soil types
- Reproduces by seeds
- Self-fertile
- Able to reach maturity in <1 year
- Seeds dispersed by wind, internally by animals, attached to vehicles, and as a crop contaminant
- Prolific seed production
- Some seeds may persist in seed bank beyond 1 year
Low Risk Traits:
- Unarmed (no spines, thorns, or burrs)
- Provides fodder for livestock
- Herbicides may provide effective control
