Family: Rhamnaceae
Origin, Description & Uses
Rhamnus alaternus, commonly known as blow-fly-bush, Italian buckthorn, or Mediterranean buckthorn, is an evergreen shrub or small tree native to the Mediterranean region. It typically grows as a dense, rounded plant with leathery dark green leaves, small yellow-green flowers, and clusters of red berries that mature to black. This hardy species is well adapted to dry climates and poor soils, making it popular in landscaping as a hedge, screen, or ornamental shrub. It has also been used in traditional medicine and valued for its tolerance to drought, wind, and coastal conditions.
Risks & Threats
Although Rhamnus alaternus is not currently known to be naturalized in the Hawaiian Islands, it possesses several traits that raise concern for tropical island ecosystems. The species produces abundant bird-dispersed seeds, forms dense thickets, and tolerates a wide range of environmental conditions, all of which may allow it to spread beyond cultivation. In regions where it has established outside its native range, it can compete with native vegetation and alter natural plant communities. Because Hawaii’s ecosystems are especially vulnerable to invasive plants, introducing species with aggressive growth and dispersal traits may increase ecological risks. For these reasons, choosing a low risk or native alternative is recommended whenever suitable options are available.
High Risk Traits:
- Environmental weed
- Congeneric weed
- Host for pests/pathogens
- Toxic to humans (allergies or other)
- Shade tolerant
- Tolerant of wide soil range
- Forms dense thickets
- Bird-dispersed seeds
- Seeds survive gut passage
- Tolerates mutilation, cultivation, or fire
Low Risk Traits:
- Self-incompatible
- No vegetative spread
- Not a prolific seed producer
- Well controlled by herbicides
