Family: Phyllanthaceae

Origin, Description & Uses
Phyllanthus amarus, commonly known as black catnip, child pick-a-back, or shatterstone, is a small tropical herb native to southern Mexico, Central America, South America, and the Caribbean. It typically grows low to the ground with slender stems, tiny green leaves arranged in rows, and small inconspicuous flowers and seed capsules beneath the leaves. This species is often found growing in disturbed sites, gardens, roadsides, lawns, and agricultural areas. In many parts of the world, it has been used in traditional herbal medicine for a variety of purposes, particularly in remedies associated with liver, kidney, and digestive health.

Risks & Threats
Phyllanthus amarus is naturalized on Oʻahu and possesses traits that are cause for concern in Hawaiʻi and other tropical island ecosystems. It grows rapidly, produces abundant seeds, and can quickly colonize disturbed habitats, allowing it to spread into cultivated and natural areas. Dense populations may compete with native vegetation and contribute to the displacement of desirable groundcover species. Because tropical islands are especially vulnerable to invasive plants, the continued spread of this species could negatively impact ecosystem health and biodiversity. For these reasons, Plant Pono considers this a high risk species, and recommends choosing low risk or native alternatives whenever suitable options are available.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Thrives in tropical climates
  
• Widely naturalized
  
• Crop weed of Bananas, Cereals, Cotton, Orchards and Plantations, Pastures, Vegetables
  
• Other Phyllanthus species have become invasive
  
• Shade-tolerant
  
• Reproduces by seeds
  
• Seeds dispersed by wind, as a contaminant, by vehicles and intentionally by people
  
• Annual life cycle

Low Risk Traits:

• Unarmed (no spines, thorns or burrs)
  
• Provides fodder for livestock
  
• Edible and medicinal uses
  
• Not reported to spread vegetatively
  
• Herbicides provide effective control