Family: Chenopodiaceae

Origin, Description & Uses
Dysphania ambrosioides, commonly known as American wormseed, epazote, or paico, is a strongly aromatic herb native to Central and South America. It has been widely cultivated and introduced to tropical and subtropical regions worldwide. This fast-growing annual or short-lived perennial typically reaches 2–4 feet tall and has narrow, irregularly toothed leaves and clusters of small green flowers along upright stems. The plant is known for its strong, pungent scent. It has a long history of use in traditional medicine—especially as a remedy for intestinal worms—and is also used in Latin American cooking, where small amounts are added to beans and other dishes for flavor.

Risks & Threats
In Hawaiʻi, American wormseed is naturalized on Kauaʻi, Oʻahu, Lānaʻi, Maui, and Hawaiʻi Island. It spreads readily in disturbed sites such as roadsides, gardens, agricultural lands, and dry open areas. The plant produces abundant seed, grows quickly, and tolerates a range of environmental conditions—traits that are cause for concern. Because it is already naturalized and capable of rapid spread, it has the potential to outcompete native plants and alter sensitive tropical island ecosystems. For these reasons, it is considered high risk. Plant Pono recommends choosing a low-risk or native alternative to help protect Hawaiʻi’s unique natural environments.

High Risk Traits:

• Naturalized: Extensively naturalized in Hawaii and South Africa.
  
• Agricultural Weed: A nearly worldwide weed of crops, orchards, and pastures.
  
• Climate Versatility: Tolerates a wide range of temperatures, precipitation, and elevations.
  
• Toxic: Causes nitrate poisoning in livestock; toxic to humans if misused.
  
• Broad Soil Tolerance: Grows in sand, loam, clay, and a wide pH range (5.0–8.7).
  
• Self-Pollinating: Can reproduce and form populations from a single plant.
  
• High Seed Production: Reproduces readily by seed.
  
• Multiple Dispersal Modes: Spread by water, animals, humans, and as a crop contaminant.
  
• Persistent Seed Bank: Seeds remain viable in soil for over a year.

Low Risk Traits:

• Not an Environmental Weed: No evidence of significant impact in natural ecosystems.
  
• Requires Sunlight: Cannot grow in shade.
  
• No Physical Defenses: Lacks spines, thorns, or burrs.
  
• Non-Climbing: Upright herb that does not smother other plants.
  
• Does Not Form Dense Thickets: Grows as individual plants or in loose stands.
  
• No Vegetative Spread: Reproduces by seed only; no rhizomes or fragmentation.
  
• Herbicide Control: Susceptible to pre-emergence herbicides.