Family: Proteaceae
Origin, Description & Uses:
Hakea salicifolia, commonly known as willow-leaved hakea, is a small tree or large shrub native to eastern Australia. It is valued for its graceful, narrow, willow-like leaves and clusters of small, fragrant white flowers that attract pollinators. This species is sometimes planted as an ornamental or for use in hedges and windbreaks due to its dense growth habit and tolerance of a range of environmental conditions, including drought and poor soils.
Risks & Threats:
Although Hakea salicifolia is not currently known to be naturalized in the Hawaiian Islands, it possesses several traits that raise concern. It produces abundant seeds that may be dispersed over long distances, and like other hakea species, it can form dense thickets that outcompete native vegetation and alter ecosystem structure. Its adaptability to varied conditions increases the risk of establishment in sensitive habitats. If introduced and spread, it could detrimentally impact tropical island ecosystems. If this plant is being considered for cultivation, it is recommended to choose a low-risk or native alternative to help protect Hawaii’s unique environment.
High Risk Traits:
- Naturalized in South Africa, New Zealand, Portugal
- Environmental weed: forms dense thickets, reduces native diversity
- Congeneric weeds exist (e.g., H. sericea)
- Tolerates wide range of soils and climates (USDA 8-10)
- Produces abundant, long-lived, viable seeds
- Canopy-stored seed bank (serotiny)
- Wind- and water-dispersed seeds
- Intentionally spread by people (hedges, nurseries)
- Benefits from fire and mutilation (post-fire seed release)
- Resprouts from cut stumps if untreated
Low Risk Traits:
- No spines, thorns, or burrs
- Non-toxic to humans or animals
- Fire retardant (not a fire hazard)
- Not shade tolerant
- No vegetative reproduction (seeds only)
- No dispersal as produce contaminant
- No bird or external animal dispersal
- Controlled by herbicides (glyphosate, picloram, metsulfuron)
