Family: Brassicaceae

Origin, Description & Uses
Sweet alyssum (Lobularia maritima) is a low-growing flowering plant native to the Mediterranean region. It is a fast-spreading annual or short-lived perennial with clusters of small, fragrant white flowers, though cultivated varieties may also be pink or purple. Because of its delicate appearance and sweet scent, it is widely used as an ornamental plant in gardens, borders, groundcovers, and container plantings. It is also popular for attracting pollinators such as bees and beneficial insects, and is often used in landscaping for its ability to quickly fill bare spaces and provide seasonal color.

Risks & Threats
Sweet alyssum is naturalized across the Hawaiian Islands, including Mokupāpapa (Kure Atoll), Kuaihelani (Midway Atoll), Oʻahu, Molokaʻi, Maui, and Hawaiʻi Island. While it is often viewed as a harmless garden plant, it possesses traits that are cause for concern, including prolific seed production, rapid growth, and the ability to spread into disturbed habitats. These characteristics allow it to persist beyond cultivation and potentially compete with native plants in coastal and dryland ecosystems. Although it is not currently considered among the most aggressive invaders, its naturalization and spread in sensitive island environments means it could still contribute to long-term ecological changes. When possible, choosing low-risk or native plant alternatives is recommended to help protect Hawaii’s unique ecosystems.

High Risk Traits:

• Naturalized in tropical/subtropical climates (including Hawaii)
  
• Repeatedly introduced outside native range as a popular ornamental
  
• Naturalized beyond native range (Hawaii, California, China, Australia)
  
• Environmental weed: crowds out native plants in coastal dunes, scrub, and prairies
  
• Contributes to extinction of island endemics (Kure Atoll)
  
• Unpalatable to deer
  
• Tolerates wide range of soils (clay, sand, acidic, loam)
  
• Forms dense mats that suppress vegetation
  
• Self-compatible, produces viable seed
  
• Minimal generative time (1 year)
  
• Seeds dispersed unintentionally along roadsides
  
• Seeds dispersed intentionally by people (horticulture)
  
• Seeds dispersed by ants (myrmecochory)

Low Risk Traits:

• No spines, thorns, or burrs
  
• No evidence of toxicity to animals or humans
  
• No persistent seed bank (>80% germinate within 2 months)
  
• No vegetative fragmentation
  
• No wind or bird dispersal adaptations
  
• No evidence of high seed production per area (>1000/m²)