Family: Aizoaceae

Origin, Description & Uses
Tetragonia tetragonoides, commonly known as New Zealand spinach, is a sprawling, succulent perennial herb native to southern China, Vietnam, temperate eastern Asia, Australasia, and New Caledonia. It grows as a low, spreading groundcover with thick, triangular to diamond-shaped fleshy leaves and small yellow-green flowers that develop into distinctive horned fruits. Despite its common name, it is not a true spinach but is widely cultivated as a leafy vegetable, especially in warm climates where conventional spinach struggles in the heat. The tender leaves and shoots are eaten raw or cooked, and the plant is valued for its tolerance of drought, salty soils, and coastal conditions, making it a popular edible groundcover in gardens.

Risks & Threats
New Zealand spinach is naturalized throughout the Hawaiian Islands, including Midway Atoll, Nihoa, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Maui, and Hawaiʻi Island. It possesses several traits associated with invasive plants, including rapid growth, prolific seed production, tolerance of harsh environmental conditions, and the ability to spread into coastal and disturbed habitats. These characteristics make it a species of concern because it can form dense mats that compete with native vegetation and alter sensitive coastal plant communities, potentially detrimentally impacting tropical island ecosystems. Because it is already widespread in Hawaiʻi, further planting should be avoided, particularly near natural areas or coastlines where it is not yet well established. Existing plantings should be carefully managed to prevent further spread. When selecting edible groundcovers or leafy vegetables, choose low-risk or native alternatives whenever such options are available.

High Risk Traits:

• Broad climate suitability (temperate to tropical) and wide elevation range (>1000 m)
  
• Naturalized outside native range (Hawaii, California, Florida, Australia, Europe, Africa)
  
• Naturalized on Kuaihelani (Midway Atoll), Nihoa, and all main Hawaiian Islands (Kaua'i, O'ahu, Molokai, Lana'i, Maui, Hawai'i)
  
• Recorded as a weed in gardens, disturbed sites, and coastal habitats
  
• Tolerates drought, salt, and a wide soil pH range
  
• Smothering growth habit (decumbent/spreading)
  
• Produces viable seed and can reproduce within 1 year
  
• Propagules dispersed by water and intentionally by people
  
• Forms a persistent seed bank (viable >1 year in soil)
  
• Tolerates mutilation/cultivation

Low Risk Traits:

• No spines, thorns, or burrs
  
• Not allelopathic or parasitic
  
• Palatable to grazing animals (used as forage)
  
• Low shade tolerance (requires full sun to partial shade)
  
• No specialized dispersal adaptations for wind, birds, or external animal attachment
  
• Reproduces by seed only (no vegetative fragmentation)
  
• Not self-compatible (protogynous, requiring cross-pollination)
  
• Controlled by herbicides