Family: Tamaricaceae

Origin, Description & Uses
Tamarix aphylla, commonly known as athel tamarisk or athel tree, is native to a broad region extending from the Sahara across the Middle East to the Indian subcontinent. It is a large, fast-growing evergreen tree with slender, gray-green branchlets and tiny scale-like leaves that enable it to thrive in hot, dry, saline, and coastal environments. Because of its exceptional tolerance to drought and salt, it has been widely planted as a windbreak, shade tree, ornamental, and for erosion control. It is also used for shelterbelts and occasionally for timber and firewood.

Risks & Threats
Tamarix aphylla is considered a high-risk species for Hawaii. Although it is currently only potentially naturalized on Kauaʻi, Molokaʻi, Lānaʻi, Kahoʻolawe, and Hawaiʻi Island, it possesses traits that are cause for concern and could detrimentally impact tropical island ecosystems if it spreads further. The species is highly tolerant of harsh environmental conditions, produces abundant seed, and readily establishes in disturbed habitats, where it can compete with native vegetation and alter ecosystem processes. Because of these risks, planting this species is not recommended. Low-risk or native alternatives should be selected whenever available. Where Tamarix aphylla is already established, its use should be carefully managed and avoided in areas where it is not yet widely established to help minimize further spread and ecological impacts.

High Risk Traits:

• Hawaiian Islands status: Potentially naturalizing on Kauaʻi, Molokaʻi, Lānaʻi, Kahoʻolawe, and Hawaiʻi
  
• Invasive outside native range (Australia)
  
• Environmental weed – displaces natives
  
• Congeneric Tamarix spp. are serious weeds
  
• Allelopathic
  
• Unpalatable to livestock/wildlife
  
• Tolerates saline, alkaline, waterlogged soils
  
• Prolific seeding – ~500,000 seeds/tree
  
• Reproduces vegetatively (suckering, coppicing, fragments)
  
• Wind- and water-dispersed
  
• Resprouts after fire/mutilation

Low Risk Traits:

• Arid/subtropical; shade-intolerant
  
• No spines/thorns
  
• Non-toxic
  
• Fire-retardant (saline foliage)
  
• No persistent seed bank (viable <1 yr)
  
• Herbicide-controlled (cut-stump)